ABSTRACT. Hydrogen production through photocatalytic processes has been extensively studied as a promising route for generating clean fuels by harnessing solar energy. In this study, we propose a novel synthesis method for copper oxides via an anodizing process on 3D-printed substrates, offering good stability, low cost, and ease of fabrication. First, polylactic acid (PLA) substrates were coated with graphene paint. Subsequently, copper was electrodeposited using a two-electrode configuration, with the printed substrate as the working electrode and a copper foil as the counter electrode. Anodization process was carried out in a two-electrode cell, using the copper-coated 3D-printed substrate as the working electrode and a steel disk as the counter electrode. XRD and XPS analyses confirmed the presence of CuO and Cu₂O. Chronoamperometric measurements performed with a potentiostat/galvanostat revealed that the photocatalyst responds to visible light irradiation. Moreover, preliminary photocurrent results indicate that copper oxides exhibit electrical conductivity under light exposure, suggesting their potential as candidates for practical applications. This approach aims to simplify photocatalyst design without compromising efficiency, thereby opening new avenues for the development of sustainable hydrogen production technologies.

ABSTRACT. Water electrolysis is a clean and efficient method for hydrogen production. In anion exchange membrane electrolyzers (AEMEs), an anion conducting membrane separates the anode and cathode, allowing OH⁻ transport and avoiding gas mixing. The hydrogen evolution reaction (HER) occurs at the cathode, and the oxygen evolution reaction (OER) at the anode. These reactions require active, stable, and cost-effective electrocatalysts. Noble metals such as Pt, Ir, and Ru exhibit excellent catalytic performance but have important drawbacks, including high cost, limited availability, and susceptibility to degradation. Therefore, alternative materials with lower noble metal content are needed. In this study, La1-xSrxFeO3 (x = 0, 0.1, 0.3, 0.5) perovskites were synthesized using the Pechini method and combined with 10 wt.% Pt/C, prepared via a microwave-assisted polyol method. The resulting La1-xSrxFeO3–Pt/C composites were structurally and chemically characterized. X-ray diffraction (XRD) confirmed the formation of orthorhombic perovskite structures and revealed diffraction peaks corresponding to Pt and the carbon support in the composite materials. Increasing Sr content led to a decrease in crystallite size and an increase in porosity. SEM-EDS and XPS analyses verify the chemical composition, revealing that Sr doping enhances porosity, introduces oxygen vacancies, and alters the oxidation states of Fe and Pt. These modifications can improve the catalytic performance of the composites by optimizing their electronic properties and increasing their active surface area. Electrochemical tests demonstrate that Sr-doped composites show enhanced activity for both HER and OER compared to undoped samples, and even more, outperforming the commercial 20 wt. % Pt/C nanocatalyst in some cases. The results indicate that La1-xSrxFeO3–Pt/C composites, particularly with x = 0 and 0.5, are promising electrocatalysts offering high catalytic activity, improved stability, and reduced Pt content, making them suitable for efficient and economical AEMEs applications.

ABSTRACT. Development of hydrogen technologies at the IPN began in 2011, following the establishment of a collaboration between ESIQIE (Electrochemical Laboratory) and ESIME U Azcapotzalco (Master's Degree in Manufacturing Engineering). The strength of this collaboration lies in transforming applied science at the laboratory level into tangible products scalable at the industrial level. In this sense, it has been possible to scale from a Technological Readiness Level (TRL) 2 to a TRL 6 in hydrogen generation technology using the Alkaline Electrolysis method, with generation ranges from 300 W to 5 kW, primarily for applications towards dual combustion processes: internal and atmospheric combustion. So, A hydrogen production laboratory using alkaline electrolysis at ESIME UA was established. For the viability and application of hydrogen generated in internal combustion processes and based on the results obtained from the Business Model Canvas, it was determined that the entire value chain must be addressed, and hydrogen generation systems developed to complement the fossil fuel combustion processes of gasoline and diesel. An ecological motorcycle was adapted, and a diesel motor was powered with hydrogen. Similarly, this Laboratory develops applications in open combustion processes—hydrogen-LP gas—for which combustion chambers and atmospheric hydrogen burners have been developed. Currently, related research is being conducted to scale up the comprehensive hydrogen generation system from 5 to 10 kW. The zero-gap electrolyser has been designed. Hydrodynamic phenomena that hinder the increased efficiency of electrolysers are being addressed, and the certification of the electrolyser characterization process is being implemented in the water reuse and recycling process. These strengths have enabled the hydrogen production laboratory, established in 2023 at ESIME U Azcapotzalco, to be incorporated into the SECIHTI National Hydrogen Technologies Laboratory (LANH2) in 2024.

ABSTRACT. Mexico produces approximately 36 million spark plugs annually, generating between 2,000 and 4,000 metric tons of automotive waste. Given that each premium spark plug contains between 4 and 5 milligrams of iridium (Ir) or platinum (Pt), this waste represents a valuable secondary source of these metals. Conventional extraction of Ir and Pt—particularly through open-pit mining—involves the removal of large amounts of material to obtain only 2 to 10 grams of Ir or Pt per ton of ore, with high consumption of water, energy, and other natural resources, in addition to significant environmental impact. In this context, it becomes imperative to develop alternative methods for recovering these metals from waste. Such approaches not only reduce reliance on traditional extractive processes but also promote more efficient resource utilization through the reuse of valuable materials. Accordingly, the aim of this work is to recover iridium and platinum from used spark plugs for their reuse in the synthesis of electrocatalysts for proton exchange membrane (PEM) fuel cells, where Ir and Pt serve as electrocatalysts in the system's electrochemical reactions. The high demand and elevated cost of these metals, combined with the environmental impacts of their extraction, underscore the importance of developing efficient recovery processes from automotive solid waste. The recovery process involved dissolving the electrode core of the spark plug using electrochemical techniques to separate Ir and Pt from the remaining components. Subsequently, a selective leaching purification step was carried out to remove nickel (Ni) residues attached to the metals. The recovered Ir and Pt were characterized by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Next, platinum was dissolved in aqua regia to prepare precursor solutions used for synthesizing Pt nanoparticles, which were characterized in solution using UV-Vis spectroscopy. Once obtained, the metal nanoparticles were supported on biochar, leading to the synthesis of Ir- and Pt-based electrocatalysts. These electrocatalysts will be evaluated in a PEM fuel cell (proton exchange membrane). The electrochemical properties of the materials will be analyzed using cyclic voltammetry and linear voltammetry to determine their catalytic activity.

ABSTRACT. In the state of Hidalgo, specifically in the locality of La Estanzuela, several freshwater bodies serve as a key economic resource for local families. An example is the “El Cedral” reservoir, which is used for recreational purposes and as an aquaculture farm. During the peak activity months, from June to August, the aquatic plant Ceratophyllum demersum proliferates and blooms extensively in the reservoir. This phenomenon poses a significant ecological and aesthetic issue, as the plant competes with native species for oxygen and nutrients. Local residents manually remove the plant once or twice a week and incinerate it using fossil fuels. This study explores the valorization of Ceratophyllum demersum as a biomass source for biochar production, with the objective of utilizing the resulting material as a support for electrocatalysts in hydrogen production. The physicochemical characterization of samples derived from the aquatic plant was conducted using FTIR, XRD, Raman spectroscopy, SEM, and BET surface area analysis. The biochar production process involved thoroughly washing the plant material, sun-drying it, and then oven-drying at 80°C for 24 hours to remove residual moisture. The dried biomass was ground and sieved to a uniform particle size of 0.1 µm. The resulting powder was chemically activated with KOH to enhance its surface area and subsequently subjected to pyrolysis. The results revealed that the synthesized biochar possesses a high fixed carbon content, graphitic structures confirmed by Raman and XRD analyses, and a large specific surface area. These features make it a promising candidate for functional support of metallic nanoparticles, such as Pt, typically used in proton exchange membrane electrolyzers to promote the hydrogen evolution reaction. This project integrates environmental sustainability by utilizing an invasive aquatic species and converting it into a high-value material. It contributes not only to the mitigation of local ecological impacts but also to the advancement of clean hydrogen generation technologies, paving the way for the use of unconventional biomasses in electrochemical applications and fostering a circular economy based on renewable local resources and low-impact technologies.

ABSTRACT. Hydrogen is increasingly recognized as a promising alternative to conventional fossil fuels, which continue to dominate the global energy sector due to their widespread availability and established infrastructure. However, the transition to a hydrogen-based energy system requires efficient and sustainable production methods. In this context, depleted hydrocarbon reservoirs represent a promising geological setting for in situ hydrogen generation and storage, offering a means of utilizing existing subsurface resources while reducing greenhouse gas emissions. This study investigates the dynamics of gas filtration and adsorption following the combustion process, with a particular focus on both the reservoir rock and the overlying caprock. Previous research has explored in situ hydrogen production through methane combustion and subsequent hydrogen generation at temperatures exceeding 1000°C. Prior to conducting filtration experiments, the physical and structural properties of the rock were analyzed using scanning electron microscopy to assess changes induced by high-temperature combustion. A custom-designed diffusion cell was utilized to simulate gas filtration under controlled laboratory conditions, allowing for a detailed examination of transport mechanisms. Additionally, hydrogen adsorption behavior was investigated under high-temperature and high-pressure conditions using numerical magnetic resonance techniques, providing insight into gas retention and mobility within the formation. Preliminary results indicate that gas transport through the reservoir rock is significantly enhanced following high-temperature treatment, likely due to thermal alteration of pore structures. In contrast, filtration through the caprock remains relatively limited, suggesting its effectiveness as a natural barrier. Furthermore, gas adsorption plays a crucial role in trapping both hydrogen and carbon dioxide during the filtration process, highlighting its potential impact on gas storage and migration mechanisms. These findings are particularly significant for field assessments when evaluating the suitability of a formation for hydrogen storage, carbon sequestration, and leakage prevention.

ABSTRACT. The continued reliance on fossil fuels for energy production remains a major environmental concern, even with recent advances in renewable technologies. This reality has driven the search for cleaner, more sustainable energy alternatives. Hydrogen has emerged as a promising energy carrier capable of meeting global energy demands while minimizing environmental impact. Recent studies have focused on materials with optical and photocatalytic properties suitable for solar-driven hydrogen production. This study investigates the synthesis and performance of strontium ferrite in two crystalline phases—spinel (SrFe₂O₄) and perovskite (SrFeO₃₋ₓ)—using the sol-gel method. These materials are attractive due to their low band gap energies, approximately 2.0 eV for SrFe₂O₄ and 1.8 eV for SrFeO₃₋ₓ, as well as their simple synthesis and environmental compatibility. The main goal is to assess the photocatalytic efficiency of these materials in hydrogen generation via bioethanol photoreforming. Unlike conventional water splitting, this process integrates photocatalysis with reforming reactions to produce hydrogen from organic feedstocks. Bioethanol, derived from renewable sources such as agricultural waste or energy crops, serves as the hydrogen donor, offering a clean and sustainable alternative to fossil fuels. Characterization of the materials included X-ray Diffraction (XRD) to confirm crystalline structure, Transmission Electron Microscopy (TEM) for morphological analysis, Diffuse Reflectance Spectroscopy to evaluate optical behavior, and Brunauer–Emmett–Teller (BET) analysis for surface area and porosity. Photocatalytic experiments were performed in a quartz reactor under visible light irradiation, simulating solar conditions. Hydrogen evolution was tracked using gas chromatography. The two ferrite phases were compared to determine which structure yields higher photocatalytic activity under solar-driven conditions. The findings aim to contribute to the development of efficient and environmentally friendly photocatalysts for hydrogen production, supporting global goals for clean energy transition and decarbonization.

ABSTRACT. The chemical or physical properties of alumina nanoclusters can be exploited for hydrogen storage. Hydrogen is an important energy carrier, exerting low environmental impact, that could be used as a sustainable energy source. Currently, efficient hydrogen storage materials constitute an important subject in material research [1-3]. The properties of α-Al2O3 are enhanced when its particle size reaches the nanoscale, resulting in a large surface area. Manipulation of matter at this scale makes it possible to exploit the best characteristics of the material and to eliminate the properties that reduce its potential. Many methods such as combustion, precipitation, mechanical milling, addition of seeding materials, synthesis of nanoclusters, vapor-phase reaction, liquid-solid-phase synthesis, and hydrothermal synthesis have been used to obtain α-Al2O3 powders. However, most of these methods employ aluminum hydrates and have their own disadvantages [4]. The challenge in the preparation of nano-α-Al2O3 powders resides on the high temperature required for the transition of γ-Al2O3 and/or θ-Al2O3 to α-Al2O3. High temperatures (>1200°C) are required to overcome the activation energy barrier and induce transformation; nevertheless, such high temperatures can also induce rapid grain growth or agglomeration of alumina particles, thus impeding the formation of nanoparticles [5]. For this reason, the synthesis of α-Al2O3 at low temperatures has been studied. In present work a simplified route to prepare α-Al2O3 nano-onions and alumina powders with an excellent surface area, through the thermal decomposition of aluminum formate (Al(O2CH)3) precursor is proposed. The calcined powders were characterized by infrared and 13C MAS NMR spectroscopy. Coordination numbers and chemical interactions were determined by 27Al MAS NMR spectroscopy. The 27Al MAS NMR spectra showed the presence of η-Al2O3 at 1000°C, and the transformation to α-Al2O3 at 1100°C. The spectral data also showed that while the precursor contained 6-coordinated aluminum ions, four-, five-, and six-coordinated aluminum species were present after calcination at 400°C. SEM images and BET measurements of α-Al2O3 revealed aggregated particles with a specific surface area of 118 m2/g.

ABSTRACT. Some medium-entropy alloys (MEAs) have promising hydrogen storage capabilities at room temperature. In this study, an equimolar MEA composed of TiVCrMn was fabricated via arc-melting and subjected to high-pressure torsion (HPT), involving 10 revolutions under a pressure of 5 GPa, and its hydrogen absorption storage properties were evaluated at room temperature under a hydrogen pressure of 25 bar. Microstructure analysis was performed using SEM-EDS and XRD techniques. XRD analyses revealed that the as-cast alloy exhibits a dual-phase microstructure comprising BCC and C14 Laves phases. Following HPT processing, the MEA developed an ultrafine structure with crystallite sizes predominantly in the 20–50 nm range. Hydrogenation experiments demonstrated a significant improvement in hysteresis behavior and cycling stability in the HPT-processed alloy compared to the as-cast counterpart. Notably, the HPT-processed MEA absorbed 1.6 wt. % hydrogen at room temperature without requiring any prior activation treatment, exhibiting rapid kinetics and full reversibility in two stages: one at room temperature and the other at high temperature (300 °C).

ABSTRACT. This study investigates the impact of inoculum origin and substrate composition on biohydrogen (H₂) production via dark fermentation (DF) using agro-industrial effluents. Four substrates were evaluated: two enzymatic hydrolysates of agave bagasse (EH1 with Celluclast/Viscozyme and EH2 with Stonezyme), acidic cheese whey (CW), and winery wastewater (WW). Each was fermented with either native microbiota or thermally pretreated anaerobic sludge to determine how microbial community structure and metabolic pathways affect H₂ yield. Pretreated sludge significantly enhanced H₂ production compared to native microbiota. For example, EH1 produced the highest hydrogen yield 842 mL H₂/L with sludge inoculum likewise 536 mL H₂/L with native microbiota. This increase was attributed to better saccharification and the enrichment of hydrogen-producing Clostridium species. Nevertheless, native microbiota exhibited broader metabolic capabilities but often diverted electrons toward propionate synthesis, resulting in lower H₂ yields. Similar trends were observed in EH2, where sludge yielded 665 mL H₂/L compared to 421 mL H₂/L with native microbiota. In CW, sludge-inoculated systems also outperformed native ones (430 vs. 304 mL H₂/L), particularly due to better lactate management. WW, however, showed minimal H₂ production under both inoculums, likely due to phenolic inhibitors. Microbial community analysis by 16S rRNA sequencing revealed distinct patterns driven by inoculum origin. Sludge-inoculated communities showed convergence across substrates, dominated by hydrogenogenic taxa such as Clostridium sensu stricto, indicating a streamlined microbial structure optimized for H₂ production. Even though native microbiota formed substrate-specific communities with higher taxonomic diversity and metabolic versatility but also increased electron diversion from hydrogenogenesis. Functional prediction using PICRUSt2 showed that sludge-derived consortia were enriched in genes related to the pyruvate: ferredoxin oxidoreductase (PFOR) and butyrate pathways—both associated with efficient H₂ production. Native microbiota, however, were enriched in genes linked to formate and propionate metabolism, indicating electron flow toward non-hydrogenogenic products. These findings confirm that sludge inoculum favor H₂-producing pathways, whereas native microbiota balance degradation versatility with lower H₂ efficiency. Despite lower yields, native microbiota demonstrated adaptability to complex substrates and potential for long-term process stability. Their ability to degrade lignocellulosic materials like agave bagasse without external enzymatic input highlights their relevance in real waste treatment scenarios. However, their tendency to promote competing metabolic pathways underlines the need for microbial management strategies, such as selective pretreatment or process control, to suppress non-H₂-producing taxa. This work underscores the importance of inoculum selection in optimizing DF. While sludge-derived inoculum maximizes H2 production through metabolic specialization, native microbiota offers resilience and substrate adaptability. Tailoring microbial communities through pretreatment, inoculum blending, and operational strategies can enhance H2 from diverse agro-industrial residues, contributing to sustainable and efficient energy recovery from waste.

ABSTRACT. Los manganatos de Litio-Níquel han sido probados como eficientes cátodos para baterías de litio, y recientemente se ha explorado su mejora mediante su dopaje con pequeñas cantidades de metales de transición como el Fe y Cr.1 Con la intensión de explorar las propiedades fotocatalíticas de estos compuestos, para potenciales aplicaciones en generación de Hidrogeno, en este trabajo se realizó la síntesis y caracterización estructural y electroquímica de manganatos de litio-níquel prístinos (LiNi0.5Mn1.5O4) y dopados con bismuto (LiNi0.5-xMn1.5-yO4:Bix+y ). La síntesis se llevó a cabo mediante el método de combustión auto propagante,2 considerando cinco estequiometrias entre los cationes Níquel:Manganeso:Bismuto, con el objeto de explorar que estequiometria favorece la integración del Bismuto en los sitios 16d de la estructura cristalina Fd3 ̅m. En las primeras dos muestras la cantidad del dopante se distribuyó homogéneamente entre los sitios del níquel y del manganeso, retirando la cantidad necesaria de estos precursores, variando la cantidad de dopante entre una y otra. En las demás 3 muestras el dopante se asignó a un solo sitio, desplazando el porcentaje equivalente del metal en cuestión, níquel o manganeso. La caracterización de difracción de rayos X (DRX) confirmó la obtención de la fase buscada en todas las muestras. Sin embargo, se encontró que la exclusión de uno de los metales se ve favorecida, observando una menor segregación de fases secundarias para un par de estequiometrías específicas. Para conocer precisamente el sitio donde se encuentra el dopante se realizó el refinamiento de Rietveld correspondiente, observándose la correcta inserción del bismuto en la fase cristalina en los sitios esperados. La morfología del material es indicativa de una posible aplicación, para observar esto se tomaron micrografías mediante la técnica de microscopía electrónica de barrido (SEM), en donde se observó alta porosidad en las muestras sintetizadas. Además de esto se realizó análisis elemental (EDS) que confirmó la presencia del bismuto. A fin de explorar la actividad electro-fotocatalítica de este nuevo material se realizó la estimación del band gap óptico y electroquímico, esto mediante reflectancia difusa por espectrofotometría UV-Vis y voltamperometría cíclica (CV), respectivamente. Los resultados de estas mediciones indican que no existe variación detrimental significativa entre el material prístino y dopado, observando en ciertas muestras una disminución del valor del band gap, óptico y electroquímico. Esto señala un posible ahorro en los costos de los precursores necesarios para producir este material. En base a los resultados de la caracterización electroquímica se exploró el potencial de este nuevo material para la generación de hidrógeno mediante fotocatálisis heterogénea, bajo irradiación UV. Como resultado se observó que, efectivamente, el material es capaz de generar hidrógeno cuando es expuesto a luz ultravioleta. Esto abre nuevas posibilidades en la aplicación de este material, ya que al ser de bajo costo y de fácil obtención se posiciona como un candidato para la generación fotocatalítica de combustibles sustentables como el Hidrógeno. Los autores expresan su agradecimiento al M.C. J. Salvador Martínez, por su apoyo en la caracterización electroquímica.

[1] Murdock, B. E., Cen, J., Squires, A. G., Kavanagh, S. R., Scanlon, D. O., Zhang, L., & Tapia‐Ruiz, N. (2024). Li‐Site Defects Induce Formation of Li‐Rich Impurity Phases: Implications for Charge Distribution and Performance of LiNi0.5−xMxMn1.5O4 Cathodes (M = Fe and Mg; x = 0.05–0.2). Advanced Materials, 36(32). https://doi.org/10.1002/adma.202400343

[2] Zhu, C., Han, C., & Akiyama, T. (2015). Controlled synthesis of LiNi0.5Mn1.5O4 cathode materials with superior electrochemical performance through urea-based solution combustion synthesis. RSC Advances, 5(62), 49831-49837. https://doi.org/10.1039/c5ra06109a

ABSTRACT. Biological hydrogen (H₂) is a clean, renewable alternative for energy production. This study evaluated graphite felt as a biofilm support during acetone-butanol-ethanol (ABE) fermentation, using a co-culture of Clostridium acetobutylicum ATCC 824 and Clostridium beijerinckii ATCC 51743, with agave lechuguilla juice as substrate. Fermentations were performed in 70 mL flasks under anaerobic conditions, using 80% juice and three graphite felt disks (1 cm diameter). After five days, cumulative hydrogen production reached 550 mL, significantly exceeding values reported for unsupported systems (~380 mL H₂). Graphite felt promoted biofilm formation and enhanced acidogenic pathways. The co-culture strategy also improved sugar utilization, delaying the onset of solventogenic metabolism and boosting hydrogen yields. The use of graphite felt created favorable microenvironments that supported higher bacterial densities and more efficient electron transfer processes, both critical for maximizing hydrogen output. The conductive nature of the material may have facilitated improved metabolic communication within the biofilm, further supporting acidogenesis over solventogenesis. Additionally, the co-culture approach allowed for broader substrate range utilization, reducing residual sugar concentrations and minimizing inhibitory byproducts. This study highlights the potential of combining conductive materials with agro-industrial residues like agave bagasse to improve biological hydrogen production. Such strategies offer a sustainable pathway for bioenergy generation while simultaneously promoting waste valorization. Future work should focus on scaling up the system, optimizing operational parameters, and evaluating the long-term stability of the biofilms under continuous fermentation conditions. These findings contribute to the development of more efficient biohydrogen production technologies and underscore the importance of integrating renewable feedstocks and advanced materials into microbial fermentation processes.

ABSTRACT. This work presents the results obtained in the preparation and optimization of catalytic inks based on mixtures of ruthenium oxide (RuO₂) and iridium oxide (IrO₂) in mass ratios 1:3, 1:1, and 3:1 to evaluate their catalytic activity towards the oxygen evolution reaction (OER) in acidic medium and their subsequent application in the preparation of membrane electrode assemblies (MEA) to be tested in a PEM electrolyzer prototype. The catalytic inks were formulated with commercial RuO₂ and IrO₂ powders dispersed in a solution based on isopropanol, 5% wt. Nafion® solution and deionized water. A three-electrode electrochemical cell was used to perform electrochemical characterization by linear and cyclic voltammetry using a glassy carbon electrode as the working electrode, a platinum mesh as the counter electrode, and a fresh hydrogen bubble electrode as the reference electrode. Baseline electrochemical profiles were obtained for each of the three inks prepared with mixtures of the different catalyst ratios, as well as for each of the RuO₂ and IrO₂ blanks separately. The linear voltammetry results revealed that the most active material toward OER was the 3:1 RuO₂-IrO₂ ratio, respectively. Once the optimal catalyst mixture was found, membrane-electrode assemblies with an active area of 5 cm² were prepared using a commercial Nafion 115 membrane. The optimal 3:1 RuO₂ - IrO₂ catalytic ink was painted as the anode material, and a commercial carbon cloth as gas diffusion layer with a catalyst loading of 40% platinum nanoparticles supported on carbon (Pt/C) was used as the cathodic material. Two painting techniques were tested: manual airbrushing and spray painting in a semi-automatic system to evaluate the best catalyst deposition method. The MEAs were sintered in a hot press at 80 °C and 150 bar. The prepared assemblies were tested in a single-cell proton exchange membrane (PEM) electrolyzer prototype built at laboratory to evaluate their performance under real-world operating conditions at 80 °C. The results obtained in MEA are consistent with those found in electrochemical tests in a three-electrode cell for the different materials studied.

ABSTRACT. Mexico is a global leader in the production of fluorspar (CaF2), the primary mineral source for obtaining fluorine. This strategic position grants Mexico a significant role in the global fluorine value chain, from raw material extraction to the production of hydrofluoric acid (HF), a key precursor in the synthesis of advanced fluorinated materials. The fluorine industry, built upon these resources and processes, is increasingly interconnected with the emerging hydrogen economy. Fluorinated compounds derived from HF are essential components in critical materials for hydrogen production, storage, and energy conversion. Notably, perfluorinated polymers are used in proton exchange membranes (PEM), and other fluorinated compounds contribute to enhanced hydrogen storage materials. The incorporation of fluorine into carbon-based materials, metal-organic frameworks (MOFs), and metal hydrides significantly improves their hydrogen adsorption capacity, thermal reversibility, and system safety. Surface fluorination alters the affinity of these materials for hydrogen, optimizing their absorption and desorption kinetics. In fluorinated MOFs, fluorine strengthens molecular interactions at low pressures, contributing to more efficient and stable hydrogen storage. This study focuses on the fluorine market within the hydrogen industry. Currently, the global market for fluorinated compounds is valued between USD 4 billion and USD 7 billion annually, with a projected compound annual growth rate (CAGR) of 10% to 15%. This growth is largely driven by increasing demand for clean hydrogen technologies. It is important to note that fluorinated membranes can account for 20% to 30% of the total cost of a PEM electrolyzer, highlighting the economic relevance of fluorine in this rapidly expanding energy value chain.

ABSTRACT. The global energy transition necessitates the decarbonisation of transportation sectors, aligning with the United Nations Sustainable Development Goals (SDGs), notably SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action). Inland water transport, often overlooked in decarbonisation strategies, presents opportunities for integrating clean energy technologies. This work examines Lake Pátzcuaro in Mexico, a UNESCO-designated Ramsar wetland (2005), where over a hundred boats propelled by internal combustion engine (ICE) facilitate essential passenger and goods transport for local communities. The reliance on fossil fuels in this fleet contributes to environmental degradation and greenhouse gas emissions. The work proposes a sustainable alternative by substituting the fossil fuel-based ICE in the boats with electrical propulsion powered with Hydrogen-based Proton Exchange Membrane Fuel Cells (PEMFCs). Supplying PEMFCs with renewable-based hydrogen offers higher energy efficiency and zero-emission operation compared to traditional ICEs. By producing hydrogen through renewable energy sources, such as on-shore and archipelago-based solar or wind power plants, the region can establish a localized, clean energy supply chain. A case study focusing on the lake's tourist transport fleet assesses the energy requirements and the hydrogen production needs, proposing an optimal sizing and allocation of on-shore hydrogen plants, considering vessel operation patterns, fleet composition, and local environmental conditions. In addition, PEMFC-powered boats can enhance air and water quality, reduce noise pollution, and promote sustainable tourism, thereby supporting broader socio-environmental objectives. This research also aims to offer a replicable and scalable model for decarbonising inland water transport in similar ecological and socio-economic contexts.

ABSTRACT. The growing demand for sustainable energy drives research into direct alcohol fuel cells (DAFCs), which convert alcohols like ethanol and glycerol into electricity. These systems offer a promising alternative to hydrogen fuel cells due to the higher energy density, lower toxicity, and easier storage of alcohols. Despite their promise, efficient alcohol electro-oxidation in DAFCs faces challenges due to slow kinetics and catalyst poisoning. Palladium (Pd)-based catalysts are a promising alternative to costly platinum (Pt) due to their catalytic activity. In these manner, PdAg and PdNi(OH)2 catalysts have shown promise, with Ag improving poisoning resistance and Ni increasing activity and selectivity. This research investigated the electro-oxidation of ethanol and glycerol using PdAg and PdNi(OH)2 electrocatalysts. The synthesis involved 2-hydroxyethylammonium formate (F2HEA) as a solvent, stabilizer, and reducing agent. X-ray diffraction (XRD) confirmed the FCC crystalline structure of the synthesized Pd, PdAg, and PdNi(OH)2 nanomaterials. Pd/C exhibited characteristic metallic Pd peaks. Bimetallic PdAg diffractograms showed both Pd and Ag reflections, suggesting alloy formation and segregated crystalline phases, with Ag inducing lattice expansion. PdNi/C diffractograms showed no Ni reflections, possibly due to low concentration or amorphous state. Shifts in 2θ positions, particularly for the (111) peak, indicated electronic interactions between Pd and the co-metals affecting adsorption energies. In addition, Cyclic voltammograms in 2 M KOH revealed typical Pd electrocatalyst regions: hydrogen adsorption/desorption, capacitive, and metallic oxide formation/reduction. Differences in peak positions and shapes for bimetallic materials indicated modifications to electronic and structural properties by Ag or Ni(OH)2. For glycerol, PdNi(OH)2/C exhibited the highest current density (jp) and a lower oxidation peak potential (Ep) than Pd/C. This improved activity is attributed to electronic changes favoring alcohol adsorption and a bifunctional mechanism. Bimetallic nanomaterials, specifically Pd65Ag35/C for ethanol and Pd30Ag70/C for glycerol, showed lower onset potentials compared to Pd/C. This enhancement is linked to Ag and Ni(OH)2's ability to adsorb OH− species, promoting intermediate oxidation and preventing catalyst poisoning. These results highlight PdAg and PdNi(OH)2 bimetallic catalysts as promising candidates for DAFC applications.

ABSTRACT. In the present investigation, we report the synthesis and modification of polymeric resins with imidazole and indole for the preparation of nitrogen-doped mesoporous carbon and its subsequent evaluation as a catalyst for the oxygen reduction reaction in alkaline media for fuel cell applications. Mesoporous carbon was obtained via the polycondensation and further carbonization of modified resorcinol-formaldehyde resins using imidazole and indole (as nitrogen precursors) in different molar ratios. The effect of variation of N-dopant/resorcinol ratio was investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) techniques and the textural properties of the carbonaceous materials were studied from the N2-adsoption isotherms using the Brunauer-Emmett-Teller (BET) method. The d-spacing value of 0.38 nm calculated from the broad peak at about 23° (2θ) of the XRD patterns indicates the semi-graphitized structure of the materials, i.e., amorphous carbon having randomly oriented aromatic carbon. The electrochemical performance of the catalysts was studied by cyclic voltammetry (CV). The CV results reveal an improvement in the catalytic activity of the N-doped materials compared to MC. The ORR activity enhancement is mainly attributed to the nature of the nitrogen precursor and to the synergistic effect between the heteroatom and the carbon structure. Besides, the tolerance tests show high resistance to methanol since the Eonset of the ORR was not affected and no current peaks associated with methanol oxidation were observed. This research represents a promising strategy for developing novel and efficient metal-free electrocatalysts for the ORR.

ABSTRACT. In this work, synthesized nitrogen-doped mesoporous carbon (N-MC) with potential use as a Pt-free catalyst in anion-exchange membrane fuel cells (AEMFC’s) was obtained using melamine as nitrogen precursor by in-situ modification of resorcinol-formaldehyde (RF) resin. The RF resin (molar ratio R:F= 1:2) was modified during the synthesis with different melamine (M) molar concentrations (10, 30, 50, 70, and 90%) and thermally decomposed by pyrolysis at 900 °C to obtain N-MC. The obtained resin and N-MCs materials were characterized by FT-IR, X-ray diffraction (XRD), BET/BJH, elemental analysis, and RAMAN. The N-MC materials were evaluated as metal-free catalysts for the oxygen reduction reaction (ORR) in alkaline medium. The results of modified resins indicated changes during the condensation reaction,s and the resulting structure and textural parameter of N-MC varied significantly with M molar ratios. XRD results indicated all obtained N-MCs consist of turbostratic and partially graphitic structures, with mesoporous of irregular diameter distribution and surface areas up to 440 m2/g. N content determination indicates a range of values between 1-3%. The electrochemical studies in O2-satured 0.1 M KOH electrolyte indicated a high catalytic activity of N-MC compared to the undoped-MC in terms of limited current density (2.70 vs 2.47 mA cm-2). In addition, the Eonset of the N-MC materials was slightly lower than undoped-MC (1.06 vs 0.99 mV).

ABSTRACT. Nowadays the acid mine drainage (AMD) is a concern worldwide. Full treatment of this hazardous effluent has not been possible through a single method due to its problematic characteristics: acidic pH (pH < 4), high concentrations of sulfates, and heavy metals. This study utilized double-chamber microbial fuel cells to achieve a bioelectrochemical treatment of AMD previously alkalinized with chicken eggshells (AMD-T1). The goal of this work was to remove heavy metals and sulfates from the effluent and generate bioelectricity during the oxidation of organic matter from anaerobic sewage sludge sourced from a wastewater treatment plant. A polarization curve using 15 resistors was performed to determine the internal resistance of the devices. An external resistance (R-ext) similar to the internal resistance calculated from the polarization curve was used to close the circuit in cells operated under closed-circuit conditions. The experiment was conducted in duplicate, lasting a total of 16 days for each trial (seven days for acclimatization, one day for the polarization curve, and eight days operating under closed circuit). In total, nine cells operated under closed circuit and four cells under open circuit. Anaerobic sewage sludge was used as inoculum and organic matter source in the anodic chamber, while AMD-T1 was placed in the cathodic chamber. After filling the cells with 100 mL of effluent in each chamber, they were stabilized for seven days using an R-ext of 10 MΩ to help polarize the electrodes and simulate open circuit conditions. Subsequently, in the nine closed-circuit cells, the R-ext of 10 MΩ was replaced with a 100 kΩ resistor on the eighth day, and the cells were operated for an additional eight days with the new R-ext. The open-circuit cells operated throughout the 16-day experiment with the R-ext of 10 MΩ. The potential difference (E) was measured in all the cells during the 16 days of the experiment using a Tulmex 16-61 digital multimeter. The E value for all cells was recorded daily, every hour for eight continuous hours, and averaged as a single data point per day. Using the E values, volumetric power (Pv) and volumetric current density (J) were calculated for the cells. The average E value of the open-circuit cells was 546 ± 101 mV, while for the closed-circuit cells it was 109 ± 14 mV. Additionally, the maximum Pv and J values observed were 2.02 mW/m³ and 14.20 mA/m³, respectively. On the other hand, the bioelectrochemical treatment of AMD-T1 promoted an increase in pH by almost one unit (from pH 5.77 to 6.62). The redox potential (Eh) was also modified by the treatment, favoring a decrease from 245 to 188 mV on average. A slight removal of sulfates (13.7%) was also observed in the treated effluent. The bioelectrochemical treatment of acid mine drainage previously alkalinized with chicken eggshells resulted in improvements to parameters such as pH and Eh, generating an effluent that is less aggressive to the environment. On the other hand, it is possible to generate bioelectricity by coupling the oxidation of organic matter with the treatment of previously alkalinized AMD.

ABSTRACT. This paper presents a comprehensive review on hydrogen sustainability in Mexico. The research covers the entire hydrogen (H2) value chain, from production methods to storage, distribution, and the regulatory framework for its use in the country. Based on these elements, the sustainability of H2 in Mexico and its potential applications in the transportation sector are analyzed. Results show a diversity of methodologies to obtain hydrogen, both in terrestrial and maritime environments, leveraging renewable energy sources. The study highlights that green hydrogen could play a central role in Mexican electricity generation, particularly in regions with high growth rates in energy demand. Additionally, the research indicates that Mexico represents a viable and sustainable option for H2 production due to its geographical characteristics, projecting that by 2050, hydrogen could significantly replace fossil fuels currently used in the transportation sector.

ABSTRACT. Nitrogen oxides (NOx) are considered one of the most important families of chemical compounds, environmentally speaking, these compounds are shown to be the main causes of smog and acid rain along with SOx. Pt-Ag catalysts supported on Al2O3 promoted with tungsten oxides (WOx) deposited on cordierite ceramic structures that were prepared by the Dip-coating method for the removal of nitrogen oxides (NOx) generated from diesel engine exhaust gases using C3H8 and H2 as reductant in selective catalytic reduction (HC-SCR) were studied. The catalysts were characterized by N2 physisorption, scanning electron microscopy (SEM/EDX), transmission electron microscopy (STEM/HAADF), X-ray diffraction (XRD) and temperature programmed reduction (TPR-H2). In addition, H2 dispersion was determined. The addition of H2 (1vol.%) over the feed gases was studied in the reduction of NO compared to C3H8 evaluating at three space velocities 30,000, 70,000 and 100,000 h-1. This combination of Pt-Ag supported on Al₂O₃-WOx on cordierite monoliths was active in NO reduction and in the combustion of CO and C₃H8. Its activity in the presence of C₃H8 and the subsequent addition of H₂ as a reducing gas is based on a synthetic mixture of emission gases (CO, CO₂, NOx, O₂ and water vapor) similar to diesel engine emissions. The study combines the presence of the reducers H₂ and C₃H8 and that of small amounts of Pt, which allows higher NO conversion at low temperatures. As previously demonstrated, the use of tungsten oxides (WOx) provides greater thermal stability to alumina, since it functions as a structural promoter and there is a very strong interaction between WOx and γ-Al₂O₃. This effect helps maintain a high support area after high temperature heat treatments (above 750°C). Using STEM, it was observed that small Pt-Ag particles (20 nm) exhibited a high Pt concentration (58.6 atomic%). Separate Ag particles were also found. The optimal preparation conditions were 3 to 4 impregnations with AlO(OH), successive impregnations starting with H₂PtCl₃ and calcination in air flow at 500°C. Based on the results obtained, a one-dimensional model of NO conversion was proposed as a function of reactor length.

ABSTRACT. Among the different means for energy production, solid oxide fuel cells (SOFC) have gained significant importance in recent decades. These electrochemical devices offer the possibility to produce electrical energy with high efficiency without any polluting byproducts, if hydrogen is used as the fuel. The electrolyte of the SOFC has various requirements for its adequate performance. High densification is one of the most important parameters that influence ionic conductivity on solid electrolytes. According to the literature, lithium oxide as a dopant has been poorly investigated even though it is a common sintering aid used in industry. In this work, gadolinium doped ceria (GDC) with different amounts of lithium was synthesized using mechanochemistry followed by thermal treatments for crystallization and sinterization. XRD analyses were used to observe the evolution of the phases through the milling time and the thermal treatments. Relative densities of the sintered samples were calculated, and morphological studies were carried out by using SEM. Electrical properties of the samples were analyzed by impedance spectroscopy. Results show that mechanochemistry was a suitable method to obtain partially crystalline materials with cubic structure after 20 hours of milling and fully crystalline samples were reached after firing at 1200 °C for 6 hours. Lithium improved densification of the samples reaching a maximum of 98.96%. The calculated values of ionic conductivity and activation energy were like the ones reported in the literature for similar materials.

ABSTRACT. In the context of the global energy situation, hydrogen has emerged as an excellent alternative as an energy carrier due to its high conversion efficiency and the formation of water as a product. Currently, most hydrogen is produced through the steam reforming of fossil fuels. This process requires high temperatures and pressures, which leads to CO2 emissions associated with energy consumption. Photocatalysis has emerged as a way to collect solar energy and store it as solar fuel. In this work, we present the results obtained in the production of hydrogen catalysts incorporated into polymeric resins. Following this premise, strontium iron perovskites (SrFeO3) were prepared by the sol-gel method and subsequently incorporated in different concentrations into polypropylene (PP) resins using the nonwoven fabric extrusion technique to obtain the catalyst. Both the perovskite and the catalyst were characterized by XPS, SEM and FTIR techniques. Subsequently, the catalyst was evaluated for hydrogen production of the prepared membranes. Although there are no previous reports about HER using SrFeO3 photocatalyst, the use of SrFeO3 anchored in polypropylene resin demonstrated great efficiency in hydrogen evolution, being much superior to pure perovskites such as LaFeO3 or SrTiO3. These results demonstrate that the strategies presented here can be considered as the basis for the design of a photocatalytic material.

ABSTRACT. This study explores the feasibility of nickel-based coatins for hydrogen generation by synthesis and electrochemical evaluation of coatings deposited on carbon steel (AC) in alkaline media (for hydrogen evolution). The coatings were synthesized via electrodeposition in a Watts-type bath, with variations in temperature (25°C, 45°C and 70°C) and the concentration of nickel and cobalt salts (0.001M, 0.067M, 0.134M and 0.2M) on the deposition processes of the coatings. The results indicate that homogeneous, bright and visually attractive coatings with good adhesion can be obtained at temperatures of 25°C and 45°C over a wide range of nickel and cobalt salt concentrations. The deposition mechanism changes as the proportion of salts in the bath varies. The morphologies of the coatings obtained are influenced by the deposition temperature, obtaining mainly coatings with smooth and granular morphology, as well as spinel type in the cobalt coatings obtained at 45°C. The deposition temperature influences the grain size of the deposit, resulting in finer grains at 25°C and larger grains at 45°C. The functional evaluation was performed in alkaline medium obtaining kinetic parameters such as exchange current density (J0), double layer capacitance (Cdl), overvoltage for hydrogen evolution (ηH₂) and Tafel slope (βa). These results indicate that the coatings obtained at 25°C and 45°C with a nickel/cobalt ratio > 50 present good electrocatalytic properties to be considered an alternative material for hydrogen productionimpact of environmental changes on aquatic ecosystems, with a focus on the adaptation mechanisms of marine species in response to fluctuating water quality parameters. The experimental design includes controlled laboratory settings to simulate various environmental conditions and observe the physiological and behavioral responses of selected marine organisms. Preliminary results suggest significant correlations between water quality variations and species adaptation strategies, highlighting the importance of continuous monitoring for ecosystem management.

ABSTRACT. The photoelectrochemical conversion of carbon dioxide (CO₂) and water splitting for hydrogen (H₂) evolution into valuable chemicals and fuels offers a sustainable approach to reducing greenhouse gas emissions and promoting a circular carbon economy. Conventional photoelectrochemical cells typically rely on ruthenium-based organometallic sensitizers due to their high efficiency. However, these materials are costly, scarce, and pose environmental risks owing to their metal toxicity. As a result, there is growing interest in developing eco-friendly and cost-effective alternatives, such as natural dyes, for use as sensitizers in photoelectrochemical systems.

Natural pigments—such as chlorophyll, anthocyanins, and carotenoids—extracted from renewable sources like plants, fruits, and flowers, possess extended conjugated molecular structures that enable efficient absorption of visible light. Upon photoexcitation, these dyes generate excited electrons that can be effectively injected into semiconductor materials. This electron transfer drives the reduction of CO₂ into valuable products such as methanol, formic acid, and carbon monoxide. Simultaneously, the system can facilitate the photoelectrochemical splitting of water to produce hydrogen gas, a clean and renewable fuel. Thus, natural dye-sensitized semiconductors offer a dual-function platform for both carbon dioxide reduction and solar hydrogen generation. A critical aspect of this approach is the alignment of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of the natural dyes with the conduction and valence bands of the semiconductor. Optimizing this energy matching and improving the interface between dye molecules and semiconductor surfaces are essential for enhancing charge separation, increasing photocurrent response, and achieving efficient catalytic conversion.

Overall, this project aims to combine the advantages of abundant, low-cost natural dyes with advanced semiconductor materials to develop a sustainable, efficient, and environmentally benign photoelectrochemical platform. This research contributes significantly to the advancement of green energy technologies, enabling innovative carbon capture and utilization strategies, and supporting global efforts to mitigate climate change through renewable solar fuels and chemicals.

ABSTRACT. The increasing demand for renewable energy has driven the development of more efficient and intelligent systems for managing energy sources, with Maximum Power Point Tracking (MPPT) as a critical component in the management of photovoltaic solar panels. MPPT allows these systems to operate under optimal generation conditions despite environmental variations. However, traditional methods are rarely capable of real-time adaptation to these fluctuations, which can reduce energy efficiency. This work presents the development of an intelligent system for optimizing MPPT in solar panels by integrating automated analysis techniques and machine learning models. The primary goal is to enhance energy conversion under variable environmental conditions, providing a more efficient response to parameter variations. The system begins with real-time acquisition of various electrical and physical parameters from the panel, such as voltage, current, temperature on the surface, and irradiance. Subsequently, an automated analysis is implemented to determine which variables have the greatest impact on system efficiency. Machine learning models are trained using historical data to correlate input parameters with optimal power points (MPP). The trained models enable more accurate prediction of the optimal operating point, improving the system's responsiveness to changes in parameter conditions. Next, the model is adapted to run directly within the system, allowing for improved autonomous decision-making. This approach focuses on variables that significantly contribute to decision-making, reducing processing complexity and enabling a more efficient implementation. This eliminates the need for external resources or remote analysis platforms, supporting an autonomous solution capable of continuous real-time operation. The integration of these intelligent algorithms into the MPPT process offers an alternative to traditional control methods, allowing the system to adapt to its environment based on criteria derived from the data it acquires. This methodology can be applied in contexts that require optimized energy management, with the ability to adapt to environmental variations without constant user intervention. This system enhances significant increases in operational autonomy of solar panels by reducing dependency on external resources and promoting more efficient energy management. The employed methodology not only optimizes the use of current renewable energy sources but also addresses future challenges related to environmental variability and increasing energy demand. Integrating artificial intelligence into energy conversion systems represents a crucial step toward more efficient and sustainable resource utilization in dynamic environments. This work is part of a broader development line aimed at integrating machine learning with energy conversion systems, seeking to enhance operational autonomy and optimize the use of energy resources in dynamic environments. Potential applications include large-scale solar installations, microgrids, and other scenarios where energy efficiency is crucial. This approach not only enhances current energy conversion efficiency but also points towards future challenges and opportunities in renewable energy. By providing a robust, autonomous system, this work contributes to the development of a smarter and more sustainable energy infrastructure.

ABSTRACT. There are several projects about alkaline electrolysis process, since it is a mature and more economical technology compared to other technologies [1], currently, the works on control strategies applied to alkaline electrolysis has increased to more than 200% in the number of publications [2], highlighting controls such as PID, Predictive Control, Adaptive Control, optimal control and neural networks, this is due to it is a problem that involves multiple variables [3] and it is complicated to manipulate it manually, for this reason a controller is necessary that automatically controls and obtains the values of the variables in the electrolyzer and compensates them as required. Due to the current panorama about alkaline electrolyzers and knowing the benefits of applying predictive control to the system, it is of great importance to implement a predictive control system that considers the variables in the electrolyzer (T, I, V), since predictive control [4] is based on previous data to be able to predict its behavior in the immediate future and to be able to anticipate the response without having pronounced peaks of disturbances. To apply predictive control, it is necessary to use a transfer function, which is obtained through Matlab's System Identification tool using experimental data from the electrolyzer, in this way a function is generated that shows the behavior of the electrolyzer. This project focuses on alkaline electrolyzers without separating diaphragm (Oxyhydrogen generation), the system shows good control of the electrolyzer.

For this work the restrictions of temperature (<= 60 °C), cell voltage (<= 2.5V per cell), electrolyte concentration (27 < %KOH < 33) and current density (0.5A/cm2) are considered to find the best operating values for the electrolyzer. Figure 1 shows the system diagram, using sensors, the plant data are read and processed, and the controller stabilizes the temperature and maintains parameters within the allowed ranges.

This system is already able at laboratory scale, and it is possible to adapt it to larger electrolyzers by changing the corresponding parameters.

ABSTRACT. Currently, green energy should be efficient, versatile, and focused on effective waste reduction, rather than just serving as an alternative to traditional waste disposal methods like incineration, composting, and landfilling, which often fail to recover resources effectively. Dark fermentation can be employed to valorize various substrates, including those from domestic, industrial, or agricultural sources, converting them into biogenic hydrogen (H2) through the action of facultative and strict anaerobic bacteria. During this biological process, parameters such as pH, temperature, hydraulic retention time (HRT), and organic load rate (OLR), among others, can be crucial to favor one population or another in non-sterile mixed cultures and consequently affect the H2 production rates (HPR). In recent years, lactate-driven dark fermentation (LD-DF) has gained interest as an alternative metabolic route to produce fermentative H2 from different organic wastes. In light of this, the present research was focused on the evaluation of OLR perturbations on a two-stage LD-DF process using simulated food waste (FW) as the substrate. The experiment was carried out for 45 days in a continuous two-stage LD-DF system, which was fed with synthetic FW (at 5% total solids (TS)) at an HRT of 12 h. This LD-DF system was performed in two 1L CSTR reactors (both with 0.75 L working volume). Two OLR variables, with two replicates each, were carried out once the H2 production stability index was over a value of 0.8 for a minimum of 5 cycles in each stage. The first reactor (devoted to lactate production) remained at a pH below 4, while 6.5 pH (using 6 M NaOH) was maintained in the second reactor (devoted to lactate-based H2 production). After reaching the first period of pseudo-stability, the HPR was 3.2 ± 0.3 NL L-1 d-1. A reduction in OLR to 2.5% TS led to an average HPR of 1.7 ± 0.2 NL L-1 d-1 and a stability recovery at 6 days. Likewise, an HPR of 3.0±1.7 NL L-1 d-1 and a recovery of stability after 4 days resulted from the increase in the OLR to 7% TS. In summary, an indirect relationship between OLR and HPR has been established. The process demonstrated low robustness in response to OLR perturbations but exhibited high resilience following such disturbances. Finally, the process showed a high degree of reproducibility across the different replicates imposed.

ABSTRACT. The adoption of renewable energy technologies is pivotal in driving the shift from a carbon-dependent economy toward more sustainable market frameworks. Owing to the potential of hydrogen as an energy carrier, biotechnologies for the production of green hydrogen, particularly dark fermentation (DF), are garnering scientific attention. In this context, an experimental study was conducted to evaluate lactate-driven dark fermentation (LD-DF) in a two-stage system during continuous long-term operation. The main purpose of this study was to narrow the gap between the extensively reported short-term DF and the comparatively understudied long-term DF for hydrogen production. In addition to contributing to the escalation of the LD-DF technology, this work explores the valorization of food waste in LD-DF two-stage systems. The H2-producing reactor (hereafter referred to as R2) was inoculated with the pretreated inoculum (90 °C for 20 minutes) from a mesophilic anaerobic fermenter. The pretreated inoculum was enriched at low hydraulic residence times (HRTs) to enhance H2 production. The lactate-producing reactor (henceforth referred to as R1) was inoculated with the autochthonous microbiota of the synthetic food waste (FW) that was used as feedstock. Both R1 and R2 were operating under a working volume of 700 mL and mesophilic conditions; the pH for R2 was fixed at 6.5. The LD-DF two-stage experiment was operated for a total of 180 days, divided among four experimental stages. The working HRTs for R1 and R2, and the pH in R1, were modified across the different stages as follows: HRTs of 12 h and no pH control in R1, Stage I; HRTs of 10 h and no pH control in R1, Stage II; HRTs of 9 h and still no pH control for R1, Stage III; HRTs remained at 9 h and pH control (4.5 pH) was activated in R1, Stage IV. The H2 production performance was evaluated in R2; conversely, H2 production was non-existent in R1. The results indicated that Stage I exhibited the highest hydrogen potential, achieving a hydrogen yield (HY) of 27.46 ± 6.73 NmL H2/g VSadded, which decayed to ~17 NmL H2/g VS for Stages II-IV. The hydrogen productivity rates (HPRs) demonstrated a relatively consistent pattern, fluctuating between 1.5 and 3.5 NL H₂/L-d throughout the experiment. HPLC determination of the main organic acids in the fermentation broth highlighted the accumulation of lactic acid in R1, reaching up to ~ 8 g lactate/L in Stage I and Stage IV. The extensive lactate utilization reported in R2 reinforced LD-DF as the main metabolic pathway for hydrogen production. Finally, the H2 production stability index (HPSI) was estimated to assess the steadiness of the HPR in R2. Overall, the HPSI throughout the 180-day experiment was 82.40. In synthesis, this work proved the stability and robustness of the LD-DF technology during long-term operation in a two-stage system.

ABSTRACT. In recent years, green hydrogen production from solar energy is considered as a promising alternative to use of fossil fuels as the main source of energy and CO2 emissions, largely responsible for global warming and the greenhouse effect. Recent advances in heterogeneous photocatalysis focus on the study of composite materials with photocatalytic activity and their application in the photoreforming process of glycerol for hydrogen production. In this work, recent advances in Pt/TiO2-carbon and Cu/TiO2-carbon photocatalysts with photocatalytic activity are described, as well as their application in the photoreforming process of glycerol for hydrogen production. The first finding relates to the methodical design of the interface of TiO2-carbon composites (physical mixture, water-induced sol-gel and waterless sonication-assisted sol-gel procedures), which significantly influences the photocatalytic activity of the glycerol photoreforming process for hydrogen production compared to the reference semiconductor, TiO2 (Evonik P25). Photocatalysts synthesized by waterless sonication-assisted sol-gel method showed improved photocatalytic properties due to a band gap reduction and an improved photosensitization process compared to pure TiO2 in hydrogen production by photoreforming. The appropriate incorporation of titania into the surface groups of carbon increased the activity of the photocatalyst by a factor of 110 as compared to Evonik P25. This increase in activity was much more intense when Pt was incorporated as a co-catalyst on the TiO2-carbon composite, exerting a combined effect on the metal-semiconductor-carbon support system. In this sense, when Cu was used as a co-catalyst, a similar but less intense effect occurs, the photocatalytic activity being lower. On the other hand, it was also discovered that photodeposition using methanol as a sacrificial agent led to the preferential incorporation of Pt and Cu into the titania counterpart of the TiO2-carbon composites, greatly favoring hydrogen production.

ABSTRACT. This study addresses the development of nitrogen-doped carbonaceous materials as metal-free catalysts for application in anion exchange membrane fuel cells (AEMFC), using agro-industrial waste derived from coconut palm (Cocos nucifera), specifically the "Palma Alta del Pacífico" variety cultivated in the state of Tabasco, Mexico. Two structural fractions of the palm leaf, rachis (APR) and leaflet (APF), were processed by pyrolysis at 700 °C for 2 h under a nitrogen atmosphere, with a heating rate of 10 °C min⁻¹. Pyrolysis was carried out under both non-activated and chemically activated conditions, the latter employing a 1 M KOH solution. The resulting biocarbons exhibited predominantly amorphous structures and high specific surface areas, reaching up to 1518 m² g⁻¹ in the activated sample derived from the leaflet (APF-KPL), which enhances their potential as catalytic supports. Physicochemical characterization of the materials included Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, and CHONS elemental analysis. Subsequently, the activated biocarbons (APR-KPL and APF-KPL) were nitrogen-doped using urea as the nitrogen precursor. Electrochemical properties were evaluated via Cyclic Voltammetry and Rotating Disk Electrode (RDE) studies at different rotation rates to assess the kinetics and electron transfer pathway of the Oxygen Reduction Reaction (ORR). Overall, the nitrogen-doped biocarbons displayed promising features for their future application as electrocatalysts in the ORR within alkaline fuel cell systems.

ABSTRACT. The railway transport is related to the development of countries by improving connectivity and increasing the economy is considered the best land transport due to many advantages such as safety, economy, energy consumption, load capacity and low pollutant emissions, the freight railway produces lower emission compared to freight transportation modes such as trucks, ships and aviation and it has the capacity to move more tons per mile, Mexico is one of the fifteen most important countries in railroad freight transport furthermore allows multimodal transport of double stowage, increasing freight capacity, in our country, the transport sector is the highest energy consumer, nearly 40% of the national energy demand, in order to accomplish many goals to the decarbonization of Mexico, freight transportation must be optimized. The integration of green hydrogen to an energy system could have potential to help archive these goals, Mexico is considered one of the most promising prospects for the future hydrogen economies in Latin American, it could be assumed that combining the advantages of rail transport and hydrogen could obtain better results to have a more efficient and less polluting transport for our country. The following article evaluates the implementation of hydrogen on an existing freight railway line in Mexico, in which energy consumption is analyzed considering a diesel locomotive and adding hydrogen as a support element to the power unit. For this purpose, the principles of train-track dynamics such as forward resistance (Rat) are used, in this way the power required for the movement of freight on a railway route is determined. The results show the improvement in energy consumption with the support of hydrogen as an additional element of approximately 10-15% compared to a completely diesel element, which shows better performance compared to purely diesel locomotives. In this way, the use of diesel/hydrogen locomotives would significantly impact the reduction of emissions into the environment.

ABSTRACT. This article reports on the synthesis, characterization, catalytic activity, selectivity and stability of Pd catalysts promoted with neodymium for the thermocatalytic conversion of methane to produce hydrogen. Different characterization techniques were used such as X-ray diffraction, N2 adsorption-desorption, Transmission Electron Microscopy, High Resolution Transmission Electron Micrographs, H2 Temperature Programmed Reduction, X-ray Photoelectron Spectroscopy, Infrared Spectroscopy of Adsorbed CO and pyridine to characterize the supports and catalysts, aiming to discern their structural, textural, and morphological attributes. The purpose of this research was to analyze the performance of the catalysts of Pd/γ-Al2O3 and Pd/γ-Al2O3 promoted with Nd, as well as the influence of the different Nd loads (1 and 10 wt%) and the Pd-support interaction in the selectivity, stability and activity for the decomposition of CH4. The metal-support interaction increased with the addition of the promoter, increasing its reduction temperature, decreasing the dispersion and increasing the metal particle size. Its acidity properties and binding energies were also affected by increasing the amount of neodymium. The activities of the catalysts for methane dehydrogenation were determined from 400 to 750 °C. All Pd catalysts showed high methane conversion at 750 °C, with conversions of 72.6, 69.2 and 77.5% for PdA, PdANd1% and PdANd10% catalysts respectively. The PdANd10% catalyst had good catalytic performance and good catalytic stability; which can be attributed to the strong interaction between the metal and the support, as observed in H2-TPR and XPS analysis. In the stability test, the PdANd10% catalyst showed higher resistance to deactivation, presenting a 15.8% activity loss after 10 h continuous reaction. The catalytic properties and deactivation resistance of the Pd/alumina catalyst were improved by the addition of the promoter. The addition of neodymium benefited the active phase by improving the migration rate of coke while inhibiting its deposition on the metal surface, leading to an extension of the catalyst lifetime.

ABSTRACT. In the present work the effect of the addition of neodymium to the Pt-Pd catalyst was studied in order to obtain a greater selectivity to hydrogen in the methane thermal decomposition (MTD). The γ-Al2O3 support was prepared from the boehmite catapal B (CONDEA, high purity 99.99%, 74% AlOOH, 26% H2O), dried at 120 °C for 12 hours. After the drying procedure, the solid was calcined in air flow of 60 mL / min for 24 hours using a temperature program of 25 to 650 °C with a speed of 2 °C / min. Finally, the system was cooled to room temperature, maintaining the air flow at 60 mL / min. The γ-Al2O3-Nd2O3 supports were prepared by impregnation with the neodymium precursor salt, with concentrations of 1.0 and 10% by weight of Nd. Three Pd-Pt catalysts supported on γ-Al2O3 and γ-Al2O3-Nd2O3 were synthesized at 1 and 10% by weight. The support was placed in the flask with a small amount of water while preparing a solution of the precursor salts ( H2PtCl6 ∙ 6H2O and PdCl2), dissolved in the minimum amount of water this solution was added in to the same flask with the support and it was left stirring for 3 hours in the rotary evaporator, and wáter was removed using a 60 °C bath; The solids were dried in an oven at 120 °C for 12 hours, then calcined at 500 °C with air flow at 60 ml / min for 5 hours and finally the catalysts were reduced in a flow of 60 ml / min. H2 at 500 °C for 5 hours. Supports, and catalysts were characterized using different characterization methods such as X-ray diffraction, N2 adsorption-desorption, X-Ray photoelectron spectrometry, Temperature Programmed Reduction, infrared of CO and Pyridine, High Resolution Transmission Electron Microscopy and Temperature Programmed Oxidation analysis. The decomposition reaction of the methane was carried out in a temperature range of 400 to 750 ° C with a previous activation with nitrogen (30 ml/min at 200 ° C) and the flow of the reagent (methane) was 2 ml/min. To achieve this, an electric furnace was used with a tubular quartz reactor with a porous plate inside to contain the catalyst (50 mg). For the analysis of the reaction products a gas chromatograph Shimadzu GC-2014 was used. The results that were obtained were the following: Pt-Pd/Al2O3 catalyst showed high activity and long life for methane decomposition atreaction. The Pt-Pd/Al2O3-Nd10% catalyst showed low activity and useful life, since it was almost complety deactivated at 750°C. Pt-Pd/A catalyst precipitated carbon atoms from several facets, whereas Pt-Pd/Al2O3-Nd(1 and 10%) catalysts formed carbon nanofibers from one facet.

ABSTRACT. This study aims to design a water electrolysis cell, considering energy consumption through experimental analysis. To achieve this, gas chromatography will be used to measure the moles of hydrogen, carbon dioxide, and oxygen produced and determine their purity. This will allow for calculating the process energy and, consequently, its efficiency. A conductivity meter and a potentiometer will simultaneously be used to measure the conductivity and pH of the electrolyte, thereby obtaining data on the energy input. These results will be compared with theoretical values to validate the system's efficiency. Finally, the data obtained will be used to optimize the design, ensuring that the process is energetically cost-effective before considering its scaling.

ABSTRACT. Water management is a crucial aspect to consider in the design of an anion exchange fuel cell (AEMFC) due to its significant influence on energy conversion performance [1]. The performance of AEMFC depends on factors, including the geometry, dimensions, and material of its components, as well as its operating conditions [2]. Water involved in the oxygen reduction reaction (ORR) acts as a limiting reactant, impacting power generation and causing damage to the membrane’s functional groups. Therefore, maintaining optimal membrane hydration is essential for continuous cell operation [3]. To demonstrate the influence of flow field design on the membrane hydration state (λ_AEM) and cell performance concerning total current (I_tot) and power (W_tot) this study compares multi-channel serpentine and interdigitated flow fields of our own design, with variations in channel dimensions, spacing, and cell aspect ratio. Additionally, a commercial single-channel serpentine flow field is included for performance comparison. This approach aims to ensure efficient water distribution over the cathode, preventing membrane dehydration. Computational fluid dynamics (CFD) tools are employed to evaluate the interdependent effects of fluid velocity, concentration of electroactive species, and electrochemical conditions within the AEMFC. These simulation studies are validated by experimental data, supporting the proposed mathematical models. Commercial software is used to simultaneously solve the momentum, mass, and charge transfer equations in the three-dimensional domain of the AEMFC flow fields and membrane-electrode assembly. Experimental polarization curves are compared with simulated ones for various available flow fields. Eight flow fields were analyzed, maintaining consistent operating conditions and component types. Without altering operating conditions, a favorable reaction environment for the AEMFC, particularly for the ORR, can be achieved. The polarization curves in Figure 1a represent the average behavior of the cell, suggesting that despite the various flow fields, the design changes are not significantly impactful, especially compared to the commercial cell (Scribner). However, when observing performance indicators like I_tot, W_tot and λ_AEM, a notable difference between the proposed designs becomes evident. In this study, multi-channel serpentine flow fields with channel/spacing ratio less than one (Ch-R 0.74) increased λ_AEM more than two-fold compared to a commercial cell, as illustrated in Figure 1b. This research demonstrates that combining experimental work with simulation tools and proper mathematical models enables the design and selection of optimal flow fields for operating an AEMFC. When synergistically combined with optimization of component materials and operating conditions by other research groups, this approach can advance the development of this technology.

ABSTRACT. Green hydrogen production research with alternative methods has increased to achieve competitive costs and viable production rates. Aluminum corrosion in aqueous acid solution has proven to be a promising method. Variables such as initial temperature and pressure conditions, shape and size of the metal, presence of promoters, HCl concentration, among others can be studied in order to make the hydrogen production process more efficient. In this research, a shrinking core model was modified to describe kinetic behaviors and evaluate the feasibility of hydrogen production reactions by aluminum corrosion in aqueous solutions by varying HCl concentration (1.125 to 1.75 M) in the presence of Na2MoO4 nanoparticles as a promoter. The experiments were evaluated on a pilot-scale, the zero-reaction time was taken when aluminum was added in the reactor. Pressure and temperature variations were monitored during reaction to quantify the H2 production rates. At low HCl concentrations, the diffusion of ion species/water molecules through the AlOOH layer to the Al surface controls throughout reaction. Although, for high HCl concentrations, a sequence of two controlling stages was required: the diffusion of ion species/water molecules through the AlOOH layer to the aluminum surface, followed by the chemical reaction on the Al surface. This kinetic study provides important reactor design criteria for continuous hydrogen production.

ABSTRACT. The race for new technologies to sustain the energy demand aims at processes that count on being environmentally compatible, such as using hydrogen for energy storage or directly as fuel. One of the greenest ways to obtain it is through photocatalysis, and TiO2 is one of the most useful photocatalysts for hydrogen production. The energy band structure of TiO2 is essential for its photocatalytic applications; however, because of the quick recombination of charge carriers and the non-absorption of visible light (Eg= 3.2 eV), it has not been scalable to industrial development so far. Therefore, we have implemented a strategy to contribute a way of enhancing the photocatalytic properties of titanium dioxide, consisting of a heterojunction of TiO2 (anatase) and tungsten trioxide (WO3), using platinum (Pt) nanoparticles as co-catalyst, directed to amplify the range of light absorbed (since WO3 can absorb visible light, Eg= 2.6) and delay the process of recombination of carriers. Six samples of different XWO3/TiO2 ratios and pure TiO2 were synthesized through inverse micro-emulsion in a single-pot method. Then, their surface was modified by adding Pt nanoparticles (1%) using the ultrasound-assisted chemical deposition method. The photocatalytic experiments were carried out with a UV lamp equipped with filters (for UV and visible light) monitoring the gases generated during the reaction with a mass spectrometer and using argon (Ag) as carrier gas. The feeding stock for H2 was a water solution with methanol (CH3OH) as a sacrificial agent. The physicochemical properties were characterized through different techniques. X-ray diffraction (XRD) analysis confirmed the anatase phase for all samples and the presence of the monoclinic crystalline phase of tungsten trioxide only in the sample that contains the higher amount of WO3 (10 mol.%). This last observable indicates the possible obtaining of tungsten nanoclusters in the other xWO3/TiO2 heterojunction composites. In addition, transmission electron microscopy results displayed the presence of the tungsten clusters on TiO2 nanoparticles (for the nanocomposites that contain 0.5, 1, 1.75, 2.5, and 5 mol.%) and the presence of WO3 nanoparticles in the sample with 10 mol.%. Photoactivity results show that the heterojunctions with 0.5, 1, and 1.75 mol % of WO3 enhanced the H2 photo-production respect from the Pt-TiO2 reference sample under both irradiation source (UV and visible light), obtaining the maximum photoactivity with the material that contains a 1 mol.%. This material displayed a 1.9 and 2.5 times higher reaction rate than the reference material under UV/visible light, respectively. A possible explanation for this improvement could be associated with the formation of a heterojunction type II, which allows the electrons to be concentrated in the WO3 and the (positively charged) holes in TiO2, physically separating the charge carriers and producing a small electric field that defers the recombination process and attracts H+ ions and hydroxyl groups OH- to different sides, hence, preventing (partially) the reforming of H2O and allowing the mating of ions into H2. The part that Pt plays as a co-catalyst revolves around being an “electron trap” that directly (and primarily) enhances the reaction rate and the overall peak of hydrogen production. It is important to note that the H2 production obtained under visible light irradiation with the best photocatalysts (1 mol% of tungsten) is 30 % higher than that obtained with the Pt-TiO2 reference sample under UV irradiation. This observation opens the opportunity to use Pt-XWO3/TiO2 systems as an interesting base material for H2 photoproduction. Acknowledgements. We are thankful to PAPIIT-UNAM, Mexico for supporting the work carried out through the projects: IN116424, IN112025 and IV100124. The authors thank David. A. Dominguez, Pedro Casillas, and Josue Romero for technical assistance.

ABSTRACT. Mg-based intermetallics are promising candidates for solid-state hydrogen storage due to their high gravimetric capacity and relatively low cost. In this work, we investigate the hydrogen storage properties of multicomponent Mg₂-based materials: Mg₂(Co₁/₃Fe₁/₃Ni₁/₃), Mg₂(Cu₁/₃Fe₁/₃Ni₁/₃), Mg₂(Co₁/₃Cu₁/₃Fe₁/₃), Mg₂(Co₁/₃Cu₁/₃Ni₁/₃), and Mg₂(Co₁/₄Cu₁/₄Fe₁/₄Ni₁/₄). These systems aim to bridge the gap between classical ternary Mg-intermetallic hydrides and high-entropy alloy concepts to improve hydrogen storage performance. The hydriding and dehydriding reactions proceed via two distinct steps: the first associated with the Mg/MgH₂ equilibrium and the second involving the formation of hydrided Mg-intermetallic phases. All materials exhibited good hydrogen absorption under mild conditions (15 bar, 300 °C). Mg₂(Co₁/₃Fe₁/₃Ni₁/₃) demonstrated the best performance, reaching 3.8 wt.% hydrogen storage with a low dehydriding onset temperature of 243 °C. The presence of Cu notably increased the equilibrium pressure of the second hydriding reaction, facilitating partial dehydriding at lower temperatures (~250 °C), while Fe enhanced the initial hydrogen uptake during the MgH₂ formation step. Pressure–composition isotherm (PCI) measurements confirmed a multistep hydriding behavior with two distinct plateaus. The first plateau, related to MgH₂ formation, was slightly below the expected Mg/MgH₂ equilibrium pressure, indicating facilitated hydriding kinetics. The second plateau, corresponding to hydrided Mg-intermetallics, shifted to higher pressures in Cu-containing samples, benefiting the dehydriding reactions. X-ray diffraction and SEM analyses revealed that after hydriding, the materials retained nanoscale structures with significant amorphization, along with evidence of diffusion and partial integration of Co, Ni, and Cu into the Mg matrix. The Fe phase showed limited integration, forming discrete regions. Overall, the results highlight that combining Co, Cu, Fe, and Ni induces a synergistic effect that tailors hydriding/dehydriding thermodynamics, improves reversibility, and adjusts kinetic barriers. Mg₂(Co₁/₃Fe₁/₃Ni₁/₃) stands out as the most promising material for practical applications, balancing high storage capacity, favorable thermodynamics, and manageable operation conditions. This study underscores the potential of compositionally complex Mg-based materials for next-generation hydrogen storage technologies.

ABSTRACT. The development of efficient hydrogen storage systems remains a critical challenge in advancing hydrogen-based energy technologies. In this work, we report a straightforward and scalable synthesis of Mg₂Ni nanoparticles supported on carbon nanofibers (CNFs) with exceptionally high active material loading (50–100 wt%). The synthesis employed organometallic precursors—n-butyl-sec-butyl-magnesium and nickelocene—in a THF/hexane solvent system, yielding sub-5 nm Mg₂Ni nanoparticles through a low-temperature thermal treatment. CNFs served not only as a structural support but also played a vital role in dispersion, confinement, and thermal conductivity enhancement. Structural characterization revealed nanoparticle sizes below 5 nm, with significant agglomeration attributed to a carbon-based binder formed in situ during precursor decomposition. Among the composites, the 75 wt% Mg₂Ni–CNF material exhibited the highest hydrogen uptake of ~2.6 wt% at 300 °C with a hydriding efficiency of 96.3%, outperforming both lower- and higher-loading samples as well as a ball-milled reference material. Pressure–composition–temperature (PCT) isotherms demonstrated a strong particle-size effect on hydriding thermodynamics, as evidenced by the reduced equilibrium pressures of the nanoparticle composites compared to bulk or ball-milled analogs. X-ray diffraction, XPS, SEM, and TEM analyses confirmed the formation of Mg₂Ni nanoparticles embedded in a carbonaceous matrix, providing not only dispersion and confinement but also protection against oxidation. The CNFs played a crucial role in structural stability, particle spacing, and hydrogen diffusion. Post-hydriding TEM revealed partial particle growth due to sintering, with retained nanoscale dispersion in CNF-supported materials. While nano-sizing significantly improved hydrogen absorption kinetics and lowered equilibrium pressures, the dehydriding behavior was less favorable, suggesting limitations in reversibility and necessitating further optimization. The presence of amorphous carbon residues and unreacted intermediates likely impedes complete desorption. Nevertheless, this study highlights the potential of nanoconfined high-loading Mg₂Ni–CNF composites for practical hydrogen storage, particularly when tuning the composition and processing to balance kinetics, capacity, and reversibility.

ABSTRACT. Mg and MgH2 are attractive candidates for solid-state hydrogen storage due to their high hydrogen capacity and reversibility. However, their commercial application is limited by slow hydriding/dehydriding kinetics and high operation temperatures. This study systematically evaluates the effects of first-row transition metal chlorides (TMClₓ, where x = 2, 3, 4) as reaction accelerators, including AlCl₃ and ZrCl₄ for comparison, on the hydrogen stora ge performance of Mg/MgH₂. All samples were prepared under identical conditions using cryogenic ball milling, enabling direct comparison of catalytic effects. Hydrogen storage behavior was assessed via temperature-programmed hydriding/dehydriding (TPH/TPD) using a custom-built Sieverts-type apparatus. Among the tested chlorides, VCl₃ demonstrated the most significant improvement in both hydrogen uptake (up to 5.8 wt%) and reaction kinetics. TiCl₄, NiCl₂, and AlCl₃ also enhanced performance, while CuCl₂ and ZnCl₂ had minimal effect. Additives with higher oxidation states, particularly +3, tended to perform better than their +2 or metallic counterparts. Characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) revealed that cryogenic milling preserved additive integrity, while hydrogen cycling triggered chemical interactions, including the formation of MgCl₂ and, in some cases, intermetallic phases such as Mg₂Cu or Mg₂NiH₄. XPS data indicated binding energy shifts consistent with Mg–TM–Cl interactions, supporting a charge-transfer mechanism. Notably, AlCl₃, despite lacking d-orbitals, showed strong catalytic effects, suggesting that d-orbitals are not strictly necessary for catalytic activity. Morphological changes, such as flake formation and induced crystallographic texture contributed to improved kinetics. These structural effects, combined with the chemical nature of the additives, led to varying degrees of enhancement. Overall, this study highlights the complex interplay of oxidation state, electronegativity, chemical reactivity, and structural modification in determining the catalytic behavior of TMClₓ additives. VCl₃ stands out as a highly effective, stable, and commercially viable reaction accelerator for Mg-based hydrogen storage systems.

ABSTRACT. The development of efficient hydrogen storage materials is critical for advancing clean energy technologies. In this study, Mg(BH₄)₂–carbon nanofiber (CNF) composites were synthesized and characterized as potential solid-state hydrogen storage systems. A modified wet-chemical synthesis method, employing cooling baths, short reaction times, and diethyl ether as solvent, was used to produce composites with 25–75 wt.% Mg(BH₄)₂. The role of CNFs was to act as a structural support, improve drying, and enhance thermal conductivity. Characterization by FTIR, XRD, SEM, and TEM revealed the successful incorporation of Mg(BH₄)₂ within the CNF matrix. FTIR analysis indicated the presence of borohydride species and suggested possible formation of mixed cation borohydrides. XRD patterns showed low crystallinity and the coexistence of α- and β-Mg(BH₄)₂ polymorphs along with side products such as LiCl and residual MgCl₂. SEM and TEM images confirmed the porous three-dimensional structure, with CNFs facilitating nanoparticle dispersion and stabilization. Temperature-programmed desorption (TPD) experiments demonstrated a significant reduction in hydrogen release onset temperatures, ranging from 90 °C to 105 °C, compared to pure Mg(BH₄)₂. The composite with 25 wt.% Mg(BH₄)₂ exhibited the most favorable performance, achieving nearly complete dehydriding with 3.7 wt.% hydrogen released. Higher Mg(BH₄)₂ loadings showed increased hydrogen release but lower overall dehydriding efficiency. Dehydriding was found to proceed via formation of MgB₂, confirmed by XRD and FTIR, without evidence of stable [B₁₂H₁₂]²⁻ intermediates, which is advantageous for potential rehydrogenation. The study highlights that CNFs not only assist in the composite synthesis and drying processes but also critically enhance hydrogen desorption kinetics by providing effective nanoconfinement and heat transfer pathways. The findings demonstrate that Mg(BH₄)₂–CNF composites synthesized via a low-temperature, solution-based route offer a promising avenue for developing high-performance hydrogen storage materials.

ABSTRACT. The different components of an alkaline electrolyser, the electrodes are the most critical, accounting for 50% of the price of a device. The anodes of metallic nickel as well as their oxides are among the most active oxygen evolution (OER) electrocatalysts in alkaline media. This work used a variant of the dynamic hydrogen bubbles template (DHBT) to prepare Ni and porous Ni anodic electrodes, were prepared the electrodes through galvanoplastic technique, using a Watts bath to be deposited in AISI 304 stainless- steel substrate. A porous Ni layer of 30 μm was deposited at two current densities of 0.06 A cm-2 (NiAc06) and 0.13 A cm-2 (NiAc13), forming macropores of different sizes on the surface. A Mitutoyo micrometer model H-2781 was used to determine the thickness of the coating. Morphological, kinetic using LSV to determine the Tafel slope of the OER, and finally an electrolysis system was integrated with these anodic electrodes and tested to determine stability analysis of the electrodes. SEM micrographs showed more pores an average diameter of ~240 μm on the NiAc13 electrode. This electrode showed better activity towards the OER, the lowest Tafel slope, 60 mV dec-1, and a lower potential to generate a current of 5 mA cm-2, 1.52 V/RHE, and high stability in the porous Ni layer. The greater performance of the NiAc13 electrode is attributed to its greater surface area and more heterogeneous surface.

ABSTRACT. This study explores the synthesis and evaluation of MgSiO3 particles doped with Cu, Zn, and Ni for photocatalytic hydrogen generation. The particles were synthesized via a combustion method followed by a reflux process for metal doping. X-ray diffraction (XRD) shows an orthorrombic crystal structure, scanning electron microscopy (SEM) shows particles with rod-like shapes, and EDS corroborate the presence of doped metals in the MgSiO3 matrix. UV-Vis optical spectroscopy studies were carried out, which helped us calculate the Eg value by using Tauc Plots, and photoluminescence spectra confirmed that doping with metals delays electron-hole pair recombination. All these characteristics confirmed the successful incorporation of dopants and the preservation of the MgSiO3 crystalline structure. Photocatalytic tests performed under Hg UV irradiation revealed a significant improvement in hydrogen production by doping, with Cu-doped MgSiO3 exhibiting the highest activity at 2795.5 μmol.g-1.h-1, outperforming the undoped material by a factor 3.8. The findings highlight the remarkable potential of metal-doped MgSiO3 as an efficient photocatalyst, driving the development of sustainable technologies for hydrogen production. The incorporation of metal cations into the MgSiO3 structure not only modifies its band gap, facilitating light absorption in the visible spectrum, but also introduces crystalline defects, such as oxygen vacancies, which act as traps for charge carriers. These defects enhance electron-hole pair separation, reducing recombination and thus increasing photocatalytic efficiency.

ABSTRACT. The transition to sustainable energy sources requires technologies that reduce dependence on fossil fuels and mitigate environmental impact. Hydrogen stands out as a clean and efficient energy vector. However, its conventional production generates high CO₂ emissions and significant implementation and storage costs, limiting its ecological, economic and social viability. Microbial electrolysis cells (MEC) offer a promising alternative for green hydrogen generation. These systems use microorganisms capable of oxidizing organic matter and transferring electrons directly or through metabolites, allowing cleaner and more sustainable production. Considering the above, a proposal for a prototype of a MEC was developed, using an H-type cell operated under microaerophilic conditions, with a platinum cathode, a graphite anode for biofilm growth and a Nafion-117 cation exchange membrane. Lactobacillus casei Shirota was used in an innovative way. While it does not transfer electrons directly, it performs homolactic fermentation, producing lactic acid, which can act as an electron mediator in MECs. The fermentation requires a carbon source, mainly sugars, extracted from sotol bagasse, an underutilized agro-industrial waste with a lignocellulosic composition. The extraction of sugars was optimized by microwave irradiation with a CEM-MARS-6 system. A full 2ᵏ factorial design and response surface methodology was employed to evaluate the interaction between temperature and hydrolysis time. This allowed for polysaccharide degradation and monosaccharide release. The extract was characterized by high performance liquid chromatography (HPLC), identifying arabinose, glucose and fructose; the latter two fermentable for lactic acid and hydrogen production. MEC performance was evaluated by standard electrochemical techniques: cyclic voltammetry (CV), chronoamperometry (CA), open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). Gas chromatography (GC) quantified hydrogen production. This work supports the development of cost-effective and environmentally friendly MECs by replacing specialized microbial consortia and synthetic substrates with a probiotic and abundant waste material, aligning with the principles of the circular bioeconomy.

ABSTRACT. Due to increasing environmental pollution, transitioning to renewable energy—particularly hydrogen as a green fuel—has become one of the greatest challenges of the 21st century. Many countries are confronting this challenge implementing decarbonization strategies with an emphasis on reducing hydrogen production costs to lower overall electricity generation expenses. At present, most industrial hydrogen is produced from fossil fuels via steam reforming, which entails significant CO₂ emissions. In contrast, water electrolysis offers a cleaner, more sustainable route for green hydrogen production [2]. Given this need, a key strategy for efficient hydrogen generation is selecting electrode materials that combine high electrochemical stability, durability under prolonged operation at elevated current densities, and favorable interactions with electrolyte. Nickel foam is widely used as a catalyst support due to its high electrical conductivity, mechanical strength, and chemical compatibility with alkaline media. Furthermore, its surface properties can be enhanced by integrating active catalytic phases. Among these, the integration of metal sulfides has attracted growing interest. Compounds like VS₂ deliver enhanced electrocatalytic performance by facilitating complex multielectron redox reactions. Notably, certain sulfides participate in electron transfer processes, improving charge-transfer kinetics and formation of reactive intermediates crucial for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Consequently, VS₂ is directly grown on nickel foam via a one-step solvothermal synthesis, securing strong interfacial contact and homogeneous dispersion of active material. Our aim is to address OER kinetics by modifying anode surface to lower its overpotential and accelerate reaction rates. Additionally, we seek to boost HER activity by promoting hydrogen generation at reduced applied potentials. This dual approach accelerates OER while lowering HER energy barriers, thereby decreasing overall cell voltage and energy losses— a critical advance toward economic viability of sustainable green hydrogen technologies.

ABSTRACT. Currently, global energy needs are dominated by fossil fuels as they have been a fundamental part of industrial and economic development. However, the excessive use of fossil fuels has negatively impacted the environment due to high CO2 emissions. Therefore, the search for new routes to generate energy is being promoted. One is hydrogen production as an energy vector, using heterogeneous photocatalysis due to its almost zero greenhouse gas emissions. In this technology, the photocatalyst plays an important role in hydrogen production since a correct selection of the photocatalyst will influence the process efficiency. Therefore, the present work studies the effect of different ratios (%w/w) of Pt-Ni, used as cocatalyst (added by chemical deposition method), on the surface of the WO3-TiO2 nanocomposite (obtained by inverse microemulsion method) in H2 production by methanol-water photoreforming.

XRD results demonstrated that the anatase phase of TiO2 dominates all photocatalysts synthesized. UV-Vis spectroscopy analysis revealed that the Pt-Ni series presents, on average, a band gap of 3.0 eV. These values favor absorption towards the visible range. BET analysis results showed that the Pt-Ni series has a surface area of 110 m²/g, with an increase in pore volume and pore size; this promotes photoactivity and selectivity of the active sites. XPS and TEM results confirmed the formation of the Pt-Ni alloy. Finally, H2 production results indicated that the nanocomposite with 0.625Pt-0.375Ni %w/w (maximum metal load 1% w/w) exhibited higher photoactivity than the WO3-TiO2 nanocomposite with the other xPt-yNi ratios and monometal references. DRIFT-UV in situ analysis demonstrated that the photoactivity is mainly conditioned by the action of the Pt-Ni cocatalyst in the reaction decomposition route of the methanol.

Acknowledgements. We are thankful to PAPIIT-UNAM, Mexico for supporting the work carried out through the projects: IN116424 and IV100124. The authors thank David. A. Dominguez and Pedro Casillas assistance.

ABSTRACT. Employing effluents that are rich in lactic and acetic acids is a potentially strategy for hydrogen production; however, the effects of operational factors on the establishment of the microbial community and the overall process performance are yet to be elucidated. The research investigated how pH (5 and 7), the lactate-to-acetate ratio (1 and 2 mol/mol), and lactate concentration (5 and 10 g/L) influence hydrogen production from leachate produced by fermenting corn stover with its native microbial community. An anaerobic leach bed reactor operated for two months, with a hydraulic retention time of 24 h and a solids retention time of 5 days, produced the leachate in which lactate represented roughly 30% to 52% of the fermentation products, measured at 11.4 g/L, while acetate and butyrate were found in lesser amounts. The leachate functioned as a growth medium for the biochemical hydrogen potential test after the adjustment of different experimental conditions. The ANOVA results demonstrated that pH was responsible for 86% of the total effect, whereas the remaining two factors each contributed 5.6%. Increasing the pH from 5 to 7 resulted in a 4- to 6-fold enhancement in hydrogen production, while a doubling of lactate concentration from 5 to 10 g/L resulted in a 1.5-fold increase in hydrogen production. At a pH of 5, the levels of undissociated acetic acid varied between 607 mg/L and 2393 mg/L, whereas at pH 7, the concentrations were between 9 mg/L and 37 mg/L, suggesting a potential inhibition of lactate-consuming hydrogenogens. This investigation revealed that achieving neutral pH levels was beneficial for the proliferation of lactate-consuming hydrogenogens, while enhancing the organic load also contributed favorably to hydrogen production.

ABSTRACT. Hydrogen is increasingly recognized as an essential energy vector for decarbonising transportation, industry, and stationary power via fuel cells. The technical and economic viability of the hydrogen value chain, however, is contingent upon clean and efficient production routes. Among commercial technologies, alkaline electrolysis is the most mature and offers moderate capital costs and straightforward scalability compared with Proton Exchange Membrane (PEM) and Solid Oxide Electrolysers (SOEC). Nevertheless, contemporary alkaline systems rarely exceed an overall energy efficiency of about 50 %. In the present work, the determinants of efficiency in membrane-free alkaline electrolysers were investigated, with particular emphasis on the influence of internal flow channels on gas–liquid dynamics. Three prototype cells, each featuring a distinct internal geometry, were evaluated at 1 atm over a current-density range of 0.20–0.60 A cm⁻² by means of a regulated 80 V / 170 A power supply. Cell temperatures rose from an initial 70 °C to above 80 °C within the first hour of operation, thereby increasing ohmic resistance and the cell voltage by approximately 120 mV. Once the preset voltage limit was reached, the current decreased by roughly 25 %, producing a concomitant decline in the oxyhydrogen (HHO) flow rate and in the overall energy efficiency. A Faradaic efficiency (ηF) of 92 % was measured for a single cell; however, diminished progressively as additional cells were connected in series owing to parasitic currents through the common electrolyte. This loss was mitigated by redesigning the collectors and increasing the inter-electrode spacing. Furthermore, inadequate gas-vent routes were shown to trap bubbles, displace electrolyte, and reduce the effective electrode area. The optimized prototype, incorporating enlarged flow channels and enhanced thermal management, sustained 50 % energy efficiency at 0.5 A cm⁻², thereby demonstrating that meticulous channel design and temperature control are as pivotal as electrocatalyst selection for achieving high-performance alkaline electrolysers.

ABSTRACT. The Magallanes region offers unique conditions for wind power generation, with levelized costs of energy (LCOE) below USD 25/MWh. This, combined with the strength of its winds and its relative proximity to key international markets such as Europe and the United States, positions the area as a strategic hub for the development of green fuels.

The Haru Oni project, led by HIF Global, exemplifies this potential. In 2023, the pilot plant produced 100,000 liters of green synthetic gasoline, shipped to Hamburg, Germany. This milestone not only highlights the region’s capabilities but also paves the way for future exports of green methanol and ammonia.

However, this development faces significant challenges. Magallanes operates as an isolated power system, primarily based on thermal generation, with limited transmission capacity. In addition, existing port and transportation infrastructure—originally designed for the oil and gas industries—requires major upgrades to meet the demands of exporting green hydrogen derivatives.

ABSTRACT. This research presents a systematic review of the evolution and emerging trends in the implementation of innovative hydrogen production solutions developed by young human capital, with a focus on identifying the main technological challenges associated with these solutions. Specifically, green hydrogen production processes are highlighted. Unlike gray, blue, and turquoise variants, green hydrogen is generated through water electrolysis using electricity from renewable sources (solar and wind), thus representing a clean and sustainable energy alternative. This difference highlights the potential of green hydrogen as an environmentally friendly option. The versatility of hydrogen further enhances its value, as it enables use in electric mobility, industrial processes, and seasonal energy storage. As a result, hydrogen has become a fundamental element in the transition to a decarbonized economy, given that its production and consumption do not generate direct greenhouse gas emissions. Recognizing these benefits, countries such as Chile, Brazil, Colombia, Argentina, and Mexico are implementing national strategies to address these issues and drive adoption. These initiatives are positioning the region as a relevant player in the global green hydrogen market, leveraging Latin America's extraordinary potential for developing the hydrogen economy due to its abundant natural resources (solar radiation, wind regime, and water availability). In light of this context, the contribution of young human capital becomes particularly relevant in priority technological areas and integrated industrial applications. These contributions not only address technical aspects but also foster disruptive business models and solutions with a social impact. With this momentum, it is estimated that the projections for the period 2030-2040 point toward transformational effects, including the creation of skilled jobs, environmental mitigation, and strengthening regional energy sovereignty. To maximize these opportunities, it is recommended that young engineers and scientists develop interdisciplinary energy skills that combine technical knowledge with socioeconomic approaches, and actively participate in scientific networks, collaborative projects, and international initiatives that promote knowledge transfer and open innovation..