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Integrating electrolyzers into power systems can significantly contribute to sustainable energy via the generation of green hydrogen while also enhancing frequency stability through effective regulation of the electrolyzers' operating power. This study gives a comprehensive analysis of large-scale electrolyzer plants when providing frequency support to power systems. First, the authors present a model predictive control (MPC)-based secondary frequency controller, combined with a droop controller as the primary frequency controller and a virtual inertia controller. Additionally, the study introduces a universal system frequency response (U-SFR) modeling approach that enables high accuracy, low computation burden, and reduced initial parameters as a testbed. Finally, an in-depth analysis is conducted, focusing on different technical aspects of large-scale electrolyzer plants when providing frequency support services. Case studies integrating PEM and Alkaline electrolyzers into the modified IEEE 39-bus system with over 50% wind power penetration are conducted. It is found that the proposed U-SFR model achieves high accuracy with lower computational time compared to detailed physical models. Additionally, model predictive controllers improve frequency quality more effectively than PID and PID-FLC methods. PEM electrolyzers are found to be more efficient in providing grid frequency support than alkaline electrolyzers due to their technical characteristics. Finally, smaller hydrogen tanks may frequently breach storage constraints, negatively impacting the system's frequency response capability. • Universal system frequency response model with high accuracy and low computation time. • Model Predictive Controller for large-scale PEM and Alkaline electrolyzer plants. • Modified IEEE-39 bus system with 50% wind energy penetration as a testbed. • Technical analysis of PEM and Alkaline electrolyzers on frequency regulation capability. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Previous studies have demonstrated linear polymers embedded with B←N units display efficient photocatalytic hydrogen evolution performance, but their limited structural tunability restricts photogenerated carrier dynamics modulation. Current researches mainly focus on linear polymers, while the study of B←N units in the field of two‐dimension conjugated polymers (2DCPs) photocatalytic hydrogen evolution remains an uncultivated ground. Herein, three 2DCPs containing B←N units were synthesized and their photocatalytic hydrogen production performance was investigated. Among them, the BN‐Tz exhibited the best property with a hydrogen production rate of 89.5 μmol·h–1, while BN‐Ph and BN‐TPB were only 26.4 and 8.5 μmol·h–1, respectively. Comprehensive analyses showed that the remarkable photocatalytic ability of BN‐Tz catalyst was mainly attributed to its superior transport and separation of photogenerated carriers, as well as the ability to construct a stronger built‐in electric field and better planarity. Meanwhile, it was found that the manipulation of the electronic properties of the structures connected to the B←N unit could effectively regulate the molecular polarity, thus achieving the control of the electronic structure of the materials. This work extends the application of materials containing B←N units in photocatalysis and lays a good foundation for the subsequent design of photocatalysts containing B←N units. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Previous studies have demonstrated linear polymers embedded with B←N units display efficient photocatalytic hydrogen evolution performance, but their limited structural tunability restricts photogenerated carrier dynamics modulation. Current researches mainly focus on linear polymers, while the study of B←N units in the field of two‐dimension conjugated polymers (2DCPs) photocatalytic hydrogen evolution remains an uncultivated ground. Herein, three 2DCPs containing B←N units were synthesized and their photocatalytic hydrogen production performance was investigated. Among them, the BN‐Tz exhibited the best property with a hydrogen production rate of 89.5 μmol·h–1, while BN‐Ph and BN‐TPB were only 26.4 and 8.5 μmol·h–1, respectively. Comprehensive analyses showed that the remarkable photocatalytic ability of BN‐Tz catalyst was mainly attributed to its superior transport and separation of photogenerated carriers, as well as the ability to construct a stronger built‐in electric field and better planarity. Meanwhile, it was found that the manipulation of the electronic properties of the structures connected to the B←N unit could effectively regulate the molecular polarity, thus achieving the control of the electronic structure of the materials. This work extends the application of materials containing B←N units in photocatalysis and lays a good foundation for the subsequent design of photocatalysts containing B←N units. [ABSTRACT FROM AUTHOR]

ZnS is widely used in the photocatalytic decomposition of water to produce hydrogen due to its fast electron-hole pair generation and high negative potential. However, its absorption in the visible region is poor due to its wide band gap, and it has serious photogenerated carrier recombination problems. Herein, a shallow impurity energy level was introduced by doping the ZnS lattice with Cd. Due to its presence, electrons trying to return to the valence band are trapped and excited twice, suppressing the recombination of photogenerated carriers and greatly improving electron utilization. The Cd1.5-ZnS possesses a hydrogen production rate as high as 85722.20 μmol/g, which is 17 times higher than pure ZnS. Meanwhile, Cd1.5-ZnS has a narrower forbidden band and superior visible light absorption, and the serious photocorrosion problem of ZnS has been suppressed. This study provides a viable approach for the synthesis of photocatalysts with adjustable band gaps and enhanced hydrogen precipitation efficiency. The band gap of ZnS is narrowed by doping Cd2+ into the lattice structure of ZnS. Additionally, a shallow impurity energy level is created in close proximity to the bottom of the conduction band. This level has the capacity to trap electrons returning to the valence band from the conduction band and to excite them. thereby greatly increasing the utilization of electrons and reducing the formation of electron-hole complexes. Consequently, the Cd1.5-ZnS exhibits superior photocatalytic hydrogen production performance. [Display omitted] • Shallow impurity energy levels are introduced by Cd2+ doping to give the samples the ability to capture electrons secondarily. • The samples with the optimal Zn/Cd molar ratios exhibited photocatalytic hydrogen production rates up to 85722.20 μmol/g. • The issue of the wide bandgap of ZnS has been effectively improved. [ABSTRACT FROM AUTHOR]

Although two-stage anaerobic digestion (TSAD) is not a novel process, information of the process stability, microbial community and effective operating conditions is limited and often contradictory. In this work, the influence of different carrier materials (polyurethane foam, carbon felt, Raschig rings and a combination of carbon felt and Raschig rings) on the performance of the thermophilic TSAD of dairy wastewater was studied. The organic loading rate (OLR) in the acidogenic reactor (RH) was gradually increased from 13.74 to 32.56 g COD/(L d), and from 0.64 to 11.46 g COD/(L d) in the methanogenic reactors by correspondingly reducing the hydraulic retention time (HRT). The highest hydrogen production rate of 1280.3 mL/(L·d) and hydrogen yield of 93.2 mL/g COD were achieved at OLR of 13.74 g COD/(L·d), but hydrogen production stopped at higher OLR. The main soluble metabolites in RH were butyrate and lactate, and the microbial community was dominated by Streptococcus , Thermoanaerobacterium , Veillonellales-Selenomonadales and Pseudomonas. The highest methane production rate (2674 mL/(L·d) at HRT of 0.5 days) was observed in the reactor with polyurethane foam, while the highest methane yield (305.5 mL/g COD at HRT of 1.5 days) was obtained in a reactor containing carbon felt. Spirochaetaceae , Desulfomicrobium , Anaerolineaceae , Candidatus Caldatribacterium and Cloacimonadaceae W5 were linked to these materials and explained the highest methanogenic performance. [ABSTRACT FROM AUTHOR]

Photosynthetic hydrogen generation by cobalt(II) tris(2‐pyridylmethyl)amine (TPMA) complexes is mainly limited by protonation kinetics and decomposition routes involving demetallation. In the present work we have explored the effects of both proton shuttles and improved rigidity on the catalytic ability of cobalt(II) TPMA complexes. Remarkably, we demonstrate that, while a small enhancement in the catalytic performance is attained in a rigid cage structure, the introduction of ammonium groups as proton transfer relays in close proximity to the cobalt center allows to reach a 4‐fold increase in the quantum efficiency of H2 formation, and a surprising 22‐fold gain in the maximum turnover number, at low catalyst concentration. The beneficial role of the ammonium relays in promoting faster intramolecular proton transfer to the reduced cobalt center is documented by transient absorption spectroscopy, showcasing the great relevance of tuning the catalyst periphery to achieve efficient catalysis of solar fuel formation. [ABSTRACT FROM AUTHOR]

The water splitting activity of (111) TiO2 monolayer nanosheet and its mono and co-doped forms has been investigated by the periodic density functional theory (DFT) calculations. Upon Zr4+ mono-doping and even increasing the concentration of Zr4+ dopant, the band gap of the (111) TiO2 monolayer becomes wider than that of the corresponding pure monolayer (3.9 eV), which reduces the photocatalytic efficiency. Fortunately, (S2−, Se2−, and Te2−) mono-doping and their increased concentration can effectively decrease the band gap by introducing midgap states above the valence band edge for the relevant monolayers. Moreover, the (Zr4+-S2−), (Zr4+-Se2−), and (Zr4+-Te2−) co-doping leads to a narrowed band gap and enhances the visible-light photoactivity of the (111) TiO2 monolayer. Among considered monolayers, the Te2−-doped and (Zr4+-Te2−) co-doped (111) TiO2 monolayers are the most desirable photocatalysts for hydrogen generation in this work. [ABSTRACT FROM AUTHOR]

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This study introduces a novel method for hydrogen fuel generation using ultrasound technology through the disassociation of water into hydrogen and oxygen. The proposed experimental setup comprises several key components: a power supply, an ultrasonic generator, two transducers, a reactor vessel, two vapor traps, a condenser, a valve, a hydrogen storage, a humidity sensor and a hydrogen measurement sensor. The system operates at a power of 100 W and a frequency of 40 kHz, and the reactor vessel contains 2L of solution. The study results show a variability in hydrogen production rates under different experimental conditions. The distilled water used in the experiments at 25 °C produces hydrogen at a rate of 0.05 μmol/min, which increases to 0.066 μmol/min at 70 °C. The tap water gives hydrogen production rates ranging from 0.044 μmol/min at 25 °C to 0.06 μmol/min at 70 °C. The lake water produces hydrogen at rates between 0.036 μmol/min and 0.054 μmol/min, while the wastewater ranges from 0.028 μmol/min to 0.044 μmol/min. The present study investigates the effect of CO 2 injection into the sonoreactor on the system performance and shows that hydrogen production rates increase over a 20-min period for the water resources, with higher CO 2 flow rates leading to improved production rates. These findings demonstrate the potential of ultrasound technology for eco-friendly hydrogen production, marking a promising alternative to conventional methods and contributing valuable insights to the field of sustainable energy. [Display omitted] • The study investigates an innovative sonic method of hydrogen generation. • The present system is proposed for clean hydrogen generation. • The experiments are conducted at a frequency of 40 kHz and power of 100 ± 10 W. • The hydrogen generation is tested under various water sources at different temperatures. • The hydrogen generation is assessed by injecting CO 2 into the sonoreactor solution. [ABSTRACT FROM AUTHOR]

This review comprehensively explores the integration of photocatalytic (PC) and photoelectrocatalytic (PEC) technologies for hydrogen production via water splitting, in synergy with the efficient conversion of biomass resources. This synergistic strategy significantly boosts hydrogen production rates in both PC and PEC systems and enhances solar energy conversion efficiency. Furthermore, it enables selective conversion of cost‐effective biomass via precise modulation of catalyst structures, paving a novel pathway for green hydrogen generation and synthesis of high‐value chemicals. Specifically, the manuscript highlights recent progress in the oxidation and coupling reactions of biomass derivatives, such as methanol, ethanol, glycerol, and 5‐hydroxymethylfurfural, in PC/PEC systems. It reveals their potential to enhance hydrogen production efficiency and the synthesis of high‐value organic compounds. Future research should focus on employing in‐situ characterization techniques and theoretical simulations to deeply understand reaction mechanisms, thus advancing the field of biomass conversion through photocatalytic/photoelectrocatalytic methods. [ABSTRACT FROM AUTHOR]

A series of M/NiCo-Ferrite (M: Pt, Pd, Ru, and Rh) nanoparticles were successfully synthesized, through a facile sol–gel auto-combustion followed by impregnation-reduction approach, as a catalyst for hydrogen generation from hydrolysis of NaBH4. All synthesized samples were characterized by XRD, N2 adsorption–desorption method, ICP-OES, FE-SEM, and EDX analysis. Compared to the other samples, it was observed that the Rh/NiCo-Ferrite sample exhibited higher particle distribution and surface area. To evaluate the hydrogen generation rate, the hydrolysis was carried out at a temperature of 35 °C, with an aqueous solution containing 5 wt.% NaBH4 and 3 wt.% NaOH. The experimental findings indicate that the Rh/NiCo-Ferrite sample exhibited a superior rate of hydrogen generation, with an average value of 11,667 mL/min.gcat, compared to the other samples studied. Enhanced catalytic properties may be responsible for its high activity. In addition, the activation energy of hydrolysis of sodium borohydride over the Rh/NiCo-Ferrite sample was 54.5 kJ/mol which is lower than the activation energy of many Ferrite-based catalysts. Moreover, the re-usability test of the Rh/NiCo-Ferrite sample denoted a decline in the catalytic activity after 4 recycling experiments due to the alterations in morphology and the reduction in the quantity of active phase. [ABSTRACT FROM AUTHOR]

Previous studies have shown that partially coating electrode surfaces with patterns of 'islands' of hydrophobic tetrafluoroethylene (PTFE; Teflon) may lead to more energy efficient gas generation. This occurred because the gas bubbles formed preferentially on the PTFE, thereby freeing up the catalytically active metallic surfaces to produce the gas more efficiently. This work examined electrochemically induced hydrogen bubble formation on a nickel electrode surface that had been coated with linear patterns of PTFE. The impact of the PTFE line size (width) and degree of coverage was examined and analyzed. No improvement in electrical energy efficiency was observed up to 15 mA/cm2 when comparing the PTFE-coated electrodes with the control bare uncoated electrode. However, increasing PTFE coverage up to 15% generally improved electrolysis performance. Moreover, samples with 50% wider lines performed better (at the equivalent PTFE coverage), yielding an overpotential decline of up to 3.9% depending on the PTFE coverage. A 'bubble-scavenging' phenomenon was also observed, wherein bubbles present on the PTFE lines rapidly shrunk until they disappeared. [ABSTRACT FROM AUTHOR]

This study aimed to analyze a novel multigeneration system which uses the PTC and the PVT solar collectors as the energy sources. The main productions of this system is power, hot water, cooling, hydrogen and freshwater. The introduced system included the Rankine cycle, the double effect organic refrigeration system, the PEM electrolyzer and the RO desalination unit. The EES software was used to analyse energy, exergy, thermoeconomics and a range of parameters. As the results show, the highest amount of exergy destruction is associated with the PTC collector, ORC cycle and PEM electrolyzer, according to the exergy destruction analysis of the main cycles. The rise in the collector area, solar radiation and ORC turbine inlet temperature leads to higher levels of hydrogen and freshwater production. Moreover, investigating different working fluids in the ORC cycle proves that R141b shows the best performance from point of view of hydrogen and freshwater production rates. Furthermore, 33.49% and 13.31% are found for the energetic and the exergetic performance of the system, respectively. [ABSTRACT FROM AUTHOR]

The evaluation in the study includes assessing the energy and exergy of a novel system capable of producing cooling, heat, electricity, hot water, hydrogen, and desalinated water simultaneously. This groundbreaking system utilizes solar and geothermal energy and consists of a proton exchange membrane (PEM) electrolyzer, reverse osmosis (RO) desalination unit, an organic Rankine cycle (ORC), an absorption refrigeration cycle, and a domestic water heater. The EES software was used to perform all the analyses. An examination of the proposed system was carried out, considering both energy and exergy aspects. The results indicate that the solar collector undergoes the most exergy destruction when examined. As the volume concentration of nanoparticles increases, the turbine’s power production increases, while the thermoelectric generator’s (TEG) power generation decreases. The solar collector’s useful energy increases with higher solar irradiation but decreases as the nanoparticle percentage rises. The turbine and TEG unit produce more power when exposed to greater solar irradiation, resulting in higher rates of freshwater and hydrogen production. [ABSTRACT FROM AUTHOR]

Enhancement of the light-absorption response and utilization of the photogenerated carriers represent a robust strategy for the design of high-performance photocatalyst. In this work, grafting CoxP nanoclusters onto S-scheme heterojunction of W18O49/ZnIn2S4 (WO/ZIS-CoxP) with strong response to the ultraviolet–visible–near infrared ray (UV–vis–NIR) region has been achieved, which possesses efficient electron-transfer-channel, and boosts charge-separation and transport kinetics. The as-prepared WO/ZIS-CoxP yields an impressive solar-driven hydrogen production rate of 45 mmol·g−1·h−1. The increased photocatalytic performance is attributed to the synergistic effect of the composite catalyst: (1) The local surface plasmon resonance-induced "hot electron" injection of W18O49 significantly increases the electron density; (2) the engineered S-scheme directional electron transfer promotes charge separation and enhances the reducing capability of photoexcited electrons; and (3) CoxP as electron-trap site for accelerating surface proton reduction reaction. This work provides a platform to impart nonprecious co-catalyst for engineering S-scheme heterojunction, serving a class of efficient solar-driven photocatalyst towards hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] Methanol is a promising hydrogen carrier for fuel cell vehicles (FCVs) via methanol steam reforming (MSR) reaction. Ceria supported copper catalyst has attracted extensive attentions due to the extraordinary oxygen storage capacity and abundant oxygen vacancies. Herein, we developed a colloidal solution combustion (CSC) method to synthesize a porous Cu/CeO 2 (CSC) catalyst. Compared with Cu/CeO 2 catalysts prepared by other methods, the Cu/CeO 2 (CSC) catalyst possesses highly dispersed copper species and abundant Cu+-O v -Ce3+ sites at the copper-ceria interface, contributing to methanol conversion of 66.3 %, CO 2 selectivity of 99.2 %, and outstanding hydrogen production rate of 490 mmol g cat −1 h−1 under 250 °C. The linear correlation between TOF values and Cu+-O v -Ce3+ sites amount indicates the vital role of Cu+-O v -Ce3+ sites in MSR reaction, presenting efficient ability in activation of water. Subsequently, a deep understanding of CSC method is further presented. In addition to serving as a hard template, the colloidal silica also acts as disperser between nanoparticles, enhancing the copper-ceria interactions and facilitating the generation of Cu+-O v -Ce3+ sites. This study offers an alternative approach to synthesize highly dispersed supported copper catalysts. [ABSTRACT FROM AUTHOR]

The utilization of hydrogen as an energy carrier faces a challenge due to its limited presence in its pure form in the Earth's atmosphere, necessitating its extraction from various sources. Among hydrogen production methods, microwave-induced plasma molecular cracking shows promise as an alternative. This review explores how different operational parameters of a microwave-induced plasma system with gas-phase discharge impact hydrogen production performance. Performance indicators include hydrogen production rate, energy yield, and final hydrogen concentration. Parameters influencing hydrogen production encompass microwave power, gas flow rate, initial hydrogen concentration, steam addition, gas injection method, and plasma-forming gas type. Other vital system parameters are also discussed. Higher absorbed power leads to increased hydrogen production, albeit less efficiently. Elevated carrier gas flow rate reduces residence time, consequently lowering performance, while higher fuel gas flow rates enhance hydrogen production. Introducing steam can enhance indicators and reduce soot, and injecting fuel gas directly into the plasma torch tip yields optimal hydrogen production. Avoiding excessive power, fuel gas flow, or water vapor is important, as hydrogen saturation can limit further performance enhancement. • Microwave-induced plasma appears as a promising alternative for H 2 production. • Operational parameters' impacts on the system performance were analyzed. • Steam addition and gas injection methods' impacts on H 2 production were discussed. • Optimal practices for enhanced H 2 production were determined. [ABSTRACT FROM AUTHOR]

Among conventional hydrogen storage materials, LiBH 4 has been regarded as one of the best hydrogen transporters due to its relatively large hydrogen capacities. However, because of its extraordinarily high dehydrogenation temperatures, LiBH 4 was not suitable for hydrogen storage due to its stable thermodynamic features. Herein, we present a novel approach to LiBH 4 that uses solid-state multi-hydroxyl mannitol as a reactant, regulating hydrogen release below 69.9 °C. More than 7 wt% H 2 could be released with ultra-fast rates at 140 °C from the LiBH 4 -mannitol composite. XRD, FTIR, and SEM tests revealed that the reaction between mannitol (Hδ+) and LiBH 4 (Hδ−) to produce hydrogen was accompanied by the generation of large amounts of heat in situ, which further promoted the decomposition of LiBH 4 for hydrogen production, exceeding the theoretical dehydrogenation amount of Hδ+- Hδ− reaction. This work indicates possibilities for the development of fast and easy high-capacity hydrogen generation systems based on complex hydrides. The LiBH 4 -mannitol composites were prepared by ball-milling, and ultra-fast released 7.0 wt% hydrogen below 140 °C. Mannitol (Hδ+) reacted with LiBH 4 (Hδ−) to produce hydrogen was accompanied by the generation of large amounts of heat locally, which further promoted the decomposition of excess LiBH 4 for hydrogen production. [Display omitted] • More than 7 wt% H 2 could be ultra-fast released from LiBH 4 -mannitol composites below 140 °C. • Mannitol (Hδ+) reacted with LiBH 4 (Hδ−) to produce hydrogen. • The heat generated by dehydrogenation further promoted the decomposition of excess LiBH 4 nearby. [ABSTRACT FROM AUTHOR]

In the quest for effective photocatalysts for hydrogen production via photocatalytic water splitting, ZnIn 2 S 4 has garnered considerable attention due to its high photocatalytic hydrogen evolution capability. In this study, boron-doped ZnIn 2 S 4 was successfully synthesized via a hydrothermal method, with a small amount of cobalt phosphate (Co-Pi) decorated on its surface. The hydrogen evolution rate of boron-doped ZnIn 2 S 4 was determined to be 5.2 mmol g−1 h−1, surpassing that of pure ZnIn 2 S 4 by 1.68 times. Moreover, with the addition of Co-Pi to boron-doped ZnIn 2 S 4 , the hydrogen production rate escalated to 29.7 mmol g−1 h−1, which is 9.58 times higher compared to pure ZnIn 2 S 4. UV–vis analysis revealed that boron doping introduced new energy levels into ZnIn 2 S 4 , effectively narrowing the bandgap and enhancing light absorption wavelength range. Furthermore, PL and XPS analyses indicate that Co-Pi effectively captures photogenerated holes (h+) in ZnIn 2 S 4 , retaining photogenerated electrons and overcoming the disadvantage of electron-hole pair recombination in ZnIn 2 S 4. The doping and loading of Co-Pi as a cocatalyst ultimately contribute to enhancing hydrogen production efficiency, thereby significantly improving the photocatalytic hydrogen evolution capability of ZnIn 2 S 4. This study provides a scalable idea for designing composite catalysts in which doping and co-catalysts work together. • ZnIn 2 S 4 (ZIS) was synthesized hydrothermally using ZnCl 2 , In(NO 3) 3 ·xH 2 O, and thioacetamide (TAA) as precursors. • Defective ZnIn 2 S 4 (B-ZIS) was hydrothermally synthesized from ZIS and NaBH 4. • B-ZIS-CP composites were prepared through the in situ photodeposition of cobalt phosphide (Co-Pi) onto B-ZIS. • The composite catalysts exhibited exceptional photocatalytic activity for hydrogen evolution. • B-ZIS-CP demonstrates remarkable separation efficiency of photogenerated electron-hole pairs. [ABSTRACT FROM AUTHOR]

In this study, a bimetallic Co–Fe nanocatalyst supported on carbon quantum dots (CQDs) is introduced as an effective catalyst for promoting hydrogen generation upon hydrolysis of sodium borohydride. Hydrothermal synthesis routes were used to produce CQDs support. All samples were subjected to analysis using XRD, UV–Vis, Raman, FTIR, FESEM, EDX, and nitrogen adsorption-desorption techniques. Benefiting from the higher surface area (51 m 2 g r ), pore volume (0.200 m L g r ), and good dispersion of Co–Fe nanoparticles over the CQDs support, the CoFe/CQD spherical nanocatalysts with 5 wt.% iron content exhibited the highest catalytic activity of 20200 mL/min.g cat within only 1 min of reaction. The kinetics studies revealed a low activation energy of 48 kJ/mol over this optimum catalyst. In addition, it was found that the catalytic performance of this catalyst was decreased after 4 runs of recycling experiments. Catalyst degradation and leaching of the active phase were likely responsible for the decline in catalyst performance. [Display omitted] • Bimetallic Co–Fe nanocatalysts supported on carbon quantum dots CQDs were prepared. • The prepared catalysts were used for H 2 generation upon hydrolysis of NaBH 4. • CoFe/CQD with 5 wt% iron exhibited superior performance in the hydrolysis of NaBH 4. • CoFe/CQD with 5 wt% iron possessed a high hydrogen generation, 20200 mL/min.g cat. • The activation energy (E a) of this reaction was 49.5 kJ/mol over CoFe/CQD with 5 wt% iron. [ABSTRACT FROM AUTHOR]

The creation of hydrogen using the lower‐cost feedstock, waste organics (WOs), e. g. kitchen waste bio‐oil, is a win‐win solution, because it can both solve energy problems and reduce environmental pollution. Ultrasound has received considerable interest in organic decomposition; however, the application of ultrasound alone is not a good choice for the hydrogen production from WOs, because of the energy consumption and efficiency. To boost the hydrogen production based on ultrasonic cavitation cracking of bio‐oil, photothermal materials are introduced into the hydrogen production system to form localized hot spots. Materials carbon black (CB), carbon nanotubes (CNT), and silicon dioxide (SiO2) all exhibit significant enhancing effects on the hydrogen production from bio‐oil, and the CB exhibits the most significant strengthening effect among these materials. When the dosage of CB is 5 mg, hydrogen production rate is 180.1 μmol h−1, representing a notable 1.7‐fold increase compared to the production rate without CB. In the presence of light and ultrasound, the hydrogen production rate can be increased by 66.7‐fold compared to the situation where only light is present without ultrasound. [ABSTRACT FROM AUTHOR]

Nowadays, hydrogen is gaining attention as one of the green energy alternatives within transition to a zero-emission economy. Increasing demand for hydrogen and its production has prompted the development of low-carbon strategies and technologies for hydrogen generation from hydrocarbons. This paper provides a thorough analysis of traditional and innovative methods for hydrogen production from fossil feedstock, reviewing the critical aspects and recent advancements in the field. The paper emphasizes the potential of in situ hydrogen generation as the most promising method, taking into account CO2 emission concerns. Additionally, this study explores the use of software packages for modeling hydrogen production, outlining their advantages and disadvantages and proposing the most favorable software for in situ hydrogen generation from hydrocarbons. Subsequent analysis sheds light on the effectiveness, economic viability, environmental impact, and future perspectives of various hydrogen production technologies. • Overview of hydrogen production technologies: conventional and innovative methods. • Key issues and best practices of the latest experimental and numerical studies. • Comparative analysis of various hydrogen production technologies and approaches. • Subsurface hydrogen generation has a great development potential. • There are methods for clean hydrogen production from hydrocarbon feedstock. [ABSTRACT FROM AUTHOR]

The global annual production of plastics and tires exceeds 6.5 billion tons, with only 10% being recycled, leading to significant environmental problems. Thermochemical gasification of these waste materials offers a potential avenue for producing renewable hydrogen while harnessing underutilized carbon-based waste streams. This review highlights the research on thermochemical conversion of plastics and tires, providing key inferences regarding yield optimization, technical hurdles, and techno-economic viability. It indicates that strategic catalyst design and optimized integrated system configurations can significantly improve the hydrogen yields from plastic and tire pyrolysis/gasification. The key results of this work are that catalyzed gasification reactions show the most potential for maximizing hydrogen yield from plastic and tire waste. The related studies demonstrated that catalysts like Ni, Fe and Ce-doped mixtures can significantly increase hydrogen yield from plastic waste pyrolysis and gasification by suppressing coke formation and promoting reforming/shift reactions. Optimization of temperature, steam ratio and residence time also improves yield. Feedstock synergies exhibiting multiple reaction pathways likewise maximize yield. Computational modeling plays a valuable role by providing mechanistic insights through equilibrium and kinetic simulations. Integrated gasification with carbon/methane reforming shows potential to improve efficiency and lower costs. Techno-economic analyses indicate plastic/tire gasification may achieve cost parity with steam methane reforming through optimized integrated designs incorporating heat recovery. Integrated processes combining multiple conversion steps could further boost efficiency but require additional modeling and testing. A deeper understanding of reaction mechanisms, achieved through advanced modeling approaches, coupled with comprehensive lifecycle analyses of integrated solutions, can pinpoint optimized processing conditions and system designs capable of matching or surpassing the economic and environmental performance of conventional fossil fuel-based hydrogen production. The recommendations provided aim to guide future research prioritization, facilitating the realization of the large-scale potential inherent in waste-derived renewable hydrogen pathways. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydrogen has emerged as a promising future energy source, but efficient, eco-friendly production and storage remain challenging. Life Cycle Assessment (LCA) is crucial for evaluating environmental impacts and guiding eco-design strategies. Among emerging techniques, magnesium hydrolysis for hydrogen production has gained attention. The presented LCA of a patented Mg-alloy with carbon and nickel additives identified nickel as the primary environmental impact contributor. To mitigate this, using ternary phases with minimal nickel content is proposed. Moreover, leveraging magnesium waste presents an opportunity to give alloys a second life, while enhancing the recycling of the resulting product, Mg(OH) 2. Although LCA results show that magnesium hydrolysis has a lower environmental impact than steam reforming, further industrial-scale research is needed. This highlights the importance of ongoing investigation and refinement of magnesium hydrolysis as a green energy solution. • Recycling Mg(OH) 2 via CRT method causes nearly 90% of environmental impacts. • Recycled aluminum and ternary Mg base compounds reduces environmental impacts. • Hydrolysis with magnesium is eco-friendly but less resource-efficient than steam reforming. [ABSTRACT FROM AUTHOR]

Co–B/Chi, which is made up of highly distributed Co–B particles, was synthesized by impregnation and chemical reduction methods. Scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller adsorption and Fourier transform infrared spectroscopy analyses were used to describe the morphology and microstructure of Co–B/Chi. The synthesized catalyst showed high catalytic activity in the hydrolysis reaction of NaBH4. The unsupported Co–B samples were compared with the chitin-supported Co–B catalyst, and the result showed that higher catalytic activity and good cycling stability for NaBH4 hydrolysis were obtained with the chitin-supported catalyst. The reaction conditions were investigated to achieve high hydrogen production. The maximum rate of hydrogen production was obtained at 40 °C and 20 mg catalyst amount. At ideal conditions, the hydrolysis reaction's activation energy was determined to be 51.65 kJ mol−1. It is indicate that Co–B/Chi is a viable low-cost catalyst for the hydrolysis of NaBH4 for hydrogen production. [ABSTRACT FROM AUTHOR]

The development of highly efficient and ultrastable electrocatalysts for hydrogen generation from water/real seawater faces huge challenges. Herein, porous carbon-supported amorphous RuPt nanoclusters (Ru5.67Pt/PC) achieve mass activities of 42.28/10.93 A mgPt−1 and ultralong cycling stability in alkaline water/seawater because of the unique cluster structure and atomic Ru–Pt dual sites. [ABSTRACT FROM AUTHOR]

This paper introduces a confinement approach to enhance solid-state hydrogen storage by designing a nano-tubular and nano-fibrous structured boron-based storage medium. We detail the preparation of the confinement matrix, emphasizing its nanotubular and microfibrous structures provided by activated halloysite and sepiolite clays to achieve suitable confinement for ammonia borane (NH 3 BH 3 , AB). The thermolysis characteristics are thoroughly investigated in a lab-scale hydrogen reactor, elucidating the activation effects (thermal, acid, and both thermal-acid) on confinement and hydrogen generation performance. The resulting composite exhibits improved thermal stability and controlled hydrogen desorption characteristics, offering great promise for safe and efficient hydrogen storage applications. This research underscores the potential of tailored nanomaterials in advancing hydrogen storage technologies, with significant implications for clean energy solutions and the sustainable transportation sector. AB confined in acid-activated nano-tubular clay has shown improved hydrogen generation features at 120 °C, resulting in the highest improvement in H 2 equivalent per AB mole (98 %) and the initial hydrogen generation rate (233 %) while minimizing induction time up to 90 %. [Display omitted] • Tubular and fiber structured clays were used as ammonia borane scaffolds medium. • Halloysite and sepiolite clays were activated by thermal, acidic and combined method. • NH 3 BH 3 based nanocarriers were prepared via modified infiltration-confinement method. • Hydrogen production performance of composites were tested at 120 °C. • Acid activated composites showed the highest performance. [ABSTRACT FROM AUTHOR]

Highlights: This review systematically summarizes the source of electricity, the key choice of catalyst, and the potentiality of electrolyte for prospective hydrogen generation. Each section provides comprehensive overview, detailed comparison and obvious advantages in these system configurations. The problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. Green hydrogen from electrolysis of water has attracted widespread attention as a renewable power source. Among several hydrogen production methods, it has become the most promising technology. However, there is no large-scale renewable hydrogen production system currently that can compete with conventional fossil fuel hydrogen production. Renewable energy electrocatalytic water splitting is an ideal production technology with environmental cleanliness protection and good hydrogen purity, which meet the requirements of future development. This review summarizes and introduces the current status of hydrogen production by water splitting from three aspects: electricity, catalyst and electrolyte. In particular, the present situation and the latest progress of the key sources of power, catalytic materials and electrolyzers for electrocatalytic water splitting are introduced. Finally, the problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. It is expected that this review will have an important impact on the field of hydrogen production from water. [ABSTRACT FROM AUTHOR]

In this study, the applicability of a Co2+-doped catalyst [(Co-Ver) cat ] fabricated from clay vermiculite ore for the synthesis of hydrogen from sodium borohydride was investigated. FT-IR, XRD, SEM, Brunauer-Emmett-Teller (BET) analysis, and X-ray fluorescence (XRF) studies were used to characterize the synthesized (Co-Ver) cat. After activation with 1 M HCl, 0.15 g the 30% Co2+-doped catalyst (7% NaOH, 2.5% NaBH 4 , 30 °C process temperature) produced the maximum catalytic activity. Under these conditions, the hydrogen generation rate of 1991,39 ml g Co −1 min−1was achieved with the (Co-Ver) cat. The NaBH 4 hydrolysis reaction had an activation energy of 43.58 kJ mol−1 and a reaction rate order (n) of 0.18. It was also determined that the prepared (Co-Ver) cat exhibited good reusability. The reusability of the (Co-Ver) cat prepared from vermiculite ore was high, and 91.78% of the expected hydrogen amount was obtained as a result of its 10th use. • A cobalt doped catalyst was prepared from raw vermiculite ore for NaBH 4 hydrolysis. • The hydrogen generation rate was calculated as 1991.39 ml g Co −1 min−1 at 30 °C. • The activation energy for NaBH 4 hydrolysis was founded 43.58 kJ mol−1 [ABSTRACT FROM AUTHOR]

In this work, oxygen-doped g-C3N4 mesoporous nanosheets (O-CNS) were synthesized via a facile recrystallization method with the assistance of H2O2. The crystal phase, chemical composition, morphological structure, optical property, electronic structure and electrochemical property of the prepared O-CNS samples were well investigated. The morphological observation combined with the nitrogen adsorption–desorption results demonstrated that the prepared O-CNS samples possessed nanosheet-like morphology with a porous structure. Doping O into g-C3N4 resulted in the augmentation of the specific surface area, which could provide more active sites for photocatalytic reactions. Simultaneously, the visible light absorption capacity of O-CNS samples was boosted owing to the regulation of O doping. The built energy level induced by the O doping could accelerate the migration rate of photoinduced carriers, and the porous structure was most likely to speed up the release of hydrogen during the photocatalytic hydrogen process. Resultantly, the photocatalytic hydrogen production rate of the optimized oxygen-doped g-C3N4 nanosheets reached up to 2012.9 μmol·h−1·g−1, which was 13.4 times higher than that of bulk g-C3N4. Thus, the significantly improved photocatalytic behavior was imputed to the synergistic effect of the porous structure, the increase in active sites, and the enhancement of visible light absorption and charge separation efficiency. Our research highlights that the synergistic effect caused by element doping will make a great contribution to the remarkable improvement in photocatalytic activity, providing a new inspiration for the construction of novel catalysts. [ABSTRACT FROM AUTHOR]

Sodium zinc borohydride (NaZn(BH4)3) is an attractive hydrogen storage material due to its ease of preparation and hydrogen release aligning well with the operational conditions of proton exchange membrane fuel cells. However, a critical limitation of NaZn(BH4)3 is the loss of boron as diborane (B2H6) during hydrogen release. Herein, this work presents a straightforward approach to address this challenge. NaZn(BH4)3 is stabilized in the form of nanorods and decorated with nickel (Ni) as a catalyst. Notably, Ni‐decorated NaZn(BH4)3 exhibits pure hydrogen release at a significantly lower temperature (50 °C) compared to pristine material, which releases a substantial amount of B2H6 alongside hydrogen at 100 °C. In‐depth structural analyses reveal that Ni decoration facilitates the decomposition of B2H6 (into B and H2) near the interfaces between the shell and borohydride core within the NaZn(BH4)3 nanorods. These findings pave the way for the development of novel strategies to achieve pure hydrogen generation from various mixed‐metal complex hydrides. [ABSTRACT FROM AUTHOR]

Hydrogen has been widely recognised as a key resource in transitioning towards a sustainable and decarbonised energy future. Of the available hydrogen production processes, solid oxide electrolysis is a promising way to produce green hydrogen via high temperature electrolysis. The high conversion efficiencies of solid oxide electrolysis systems combined with the ability to integrate this technology with downstream chemical syntheses plants make them very attractive compared to other electrolysis technologies. However, solid oxide electrolysis, to date is the least developed electrolysis technology from the point of view of large-scale commercialisation. In recent years, significant research on fabrication and testing of individual solid oxide electrolyser (SOE) cells has been reported which has led to a multi-fold improvement in cell performance. Improvements on a cell level, though do not directly translate to improvements on a stack and system-level scale. Scaling-up solid oxide electrolysers for higher hydrogen production rates is challenging. This review presents an overview of the experimental and modelling investigations of the stack and system-scale SOE technology. The current commercial status of the SOE systems is highlighted and further improvements needed for successful near and long-term commercialisation of the technology are discussed. [Display omitted] • Solid oxide electrolyser systems are reviewed, with a focus on stacks and modules. • Experimental studies on solid oxide stack testing are discussed. • Numerical and system-level modelling-based studies are reviewed in depth. • Current status of commercial solid oxide electrolyser systems is highlighted. • Challenges and future outlook for the technology are discussed. [ABSTRACT FROM AUTHOR]

Highly n-doped silicon nanowires (SiNWs) exhibit excellent hydrogen generation. Our results indicate three hydrogen generation possibilities, i.e. SiNWs oxidation, photocatalysis and the cleavage of dangling H bonds, are jointly responsible for the efficient hydrogen generation. Oxidation accounts for about 80% of total hydrogen, photocatalysis contributes less than 20% of total hydrogen, and about 0.1% of total hydrogen is from cleavage of dangling H bonds. SiNWs were oxidized in water and form SiO x (0 < X < 2) thin layer. Furthermore, the ratio of photo-generated hydrogen to photo-generated oxygen is about 2.4:1. It suggests that photocatalysis appears to be a process of water splitting. This study is significant to reveal the mechanism of hydrogen production on SiNWs prepared by Metal-Assisted Wet Chemical Etching (MAWC). [Display omitted] • SiNWs were reported to produce H 2 in water as photocatalyst. However, the mechanism of hydrogen generation on SiNWs has not been clarified. Is it real water splitting? As far as We know, there is no clear conclusion on this issue at present. A accurate numerical computation of hydrogen and oxygen generation was given in the manuscript. Our results indicate SiNWs oxidation, photocatalysis and the cleavage of dangling H bonds, are jointly responsible for the efficient hydrogen generation. The ratio of photo-generated hydrogen to photo-generated oxygen is about 2.4:1, it is close to the theoretical ration of water splitting. [ABSTRACT FROM AUTHOR]

As new sources of energy and advanced technologies are used, there is a continuous evolution in energy supply, demand, and distribution. Advanced nuclear reactors and clean hydrogen have the opportunity to scale together and diversify the hydrogen production market away from fossil fuel-based production. Nevertheless, the technical uncertainties surrounding nuclear hydrogen processes necessitate thorough research and a solid development effort. This paper aims to position pink hydrogen for nuclear hydrogen production at the forefront of sustainable energy-related solutions by offering a comprehensive review of recent advancements in nuclear hydrogen production, covering both research endeavors and industrial applications. It delves into various pink hydrogen generation methodologies, elucidating their respective merits and challenges. Furthermore, this paper analyzes the evolving landscape of pink hydrogen in terms of its levelized cost by comparatively assessing different production pathways. By synthesizing insights from academic research and industrial practices, this paper provides valuable perspectives for stakeholders involved in shaping the future of nuclear hydrogen production. [ABSTRACT FROM AUTHOR]

The electrodeposition process and the subsequent assessment of a novel cuprous oxide photocathode are conducted for solar light-based hydrogen production. The mesh dome photocathode helps facilitate the optimal light harvesting, enabling the efficient collection of the maximum accessible light from the solar simulator. This particular design also ensures that light reaches the remote surfaces of the photocathode through penetrating the mesh structure. The electrodeposition method is then employed to coat cuprous oxide onto the stainless-steel electrode. The subsequent examination of this photocathode occurs within an alkaline solution of potassium dioxide to assess its performance in hydrogen production. The study investigates the impact of the new design of the mesh photocathode on hydrogen generation rates, as well as related efficiencies of energy and exergy, under varying light angles during daylight hours. The present experimental findings reveal that the maximum rates of hydrogen production, achieved at a 45° tilt light and 0.25 M KOH, are 15.38 μg/s and it is 15.83 μg/s for vertical light positions. Furthermore, the highest recorded system exergy and energy efficiencies under vertical light conditions are 2.19% and 3.20%, respectively, compared to 2.14% and 3.12% at applying tilted light. The new photocathode design contributes to a notable 80.3% improvement in hydrogen generation rate at tilted light angles in comparison to vertical light conditions. • A novel PEC Cell Design with a unique photocathode is studied experimentally. • Hydrogen generation rates are estimated for the light of 45° and 90° orientation. • Exergy and energy efficiencies of the photoelectrochemical cell are assessed. • The current hydrogen apparatus accomplishes promising hydrogen generation results. [ABSTRACT FROM AUTHOR]

This study explores the use of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) membranes for pure hydrogen production via water splitting. The membrane was coated with a BaCe0.2Fe0.8O3-δ catalyst to activate the water splitting reaction in a membrane reactor. H2O/Ar and CH4/Ar gas mixtures were supplied to the feed and sweep sides, respectively. Exit gases were analysed in situ using micro-GC. The results revealed that the hydrogen production rate increased with increasing temperature, methane, and water concentrations. The highest hydrogen production rate (0.37 µmol/cm2s) was achieved at 925 °C using 15% CH4 in the sweep and 55% H2O in the feed. On the sweep side, CH4 reacts to generate CO2 and syngas (H2 + CO) in a ratio commonly used in integrated gasification combined cycle power plants. This study highlights the potential of BSCF membranes as a promising technology for simultaneous production of pure hydrogen, on one side, and syngas through controlled reactions involving methane and permeated oxygen, on the other side. [ABSTRACT FROM AUTHOR]

Sustainable hydrogen generation is preferred over production from fossil sources in the context of a carbon‐neutral economy. As a result, production costs for CO2‐based products are estimated to be much higher than those of their fossil equivalents. Hence, it is essential to optimize process chains regarding their hydrogen efficiency. In this study, a concept for the directly coupled production of CO2‐based methanol and formaldehyde in a modified silver catalyst process is evaluated regarding the utilization of H2. Detailed simulations in Aspen Plus allow the comparison to the separately operated synthesis of green methanol and formaldehyde. By directly connecting both production steps, utilization ratios of introduced H2 and CO2 could be improved, reaching values of 98 % and 99 %, respectively. [ABSTRACT FROM AUTHOR]

With the current trends of wind energy already playing a major part in the Scottish energy supply, the capacity of wind farms is predicted to grow exponentially and reach further depths offshore. However, a key challenge that presents itself is the integration of large producing assets into the current UK grid. One potential solution to this is green hydrogen production, which is being heavily researched in industry, with many concepts being investigated for large-scale purposes. However, the operations and maintenance (O&M) costs and availability of green hydrogen systems need to be quantified to ensure economical and technical viability, which is sparse in the available literature. The study presented in this paper investigated the availability and O&M costs of coupled wind–hydrogen systems by attempting to quantify the failure rates, repair times, repair costs and number of technicians required for key green hydrogen components. This study also utilised an O&M model created by the University of Strathclyde, which uses Monte Carlo Markov chain simulations to produce the O&M outputs. A number of assumptions were made throughout the study in relation to the O&M model inputs, and the baseline availability for the coupled wind–hydrogen system was 85.24%. Whilst the wind turbine still contributed a major part to the downtime seen in the simulations, the combined hydrogen system also contributed a significant amount, a total of 37%, which could have been due to the technology readiness levels of some the components included in the hydrogen system. [ABSTRACT FROM AUTHOR]

In this article, the potential of biophotovoltaic devices (BPVs) as a sustainable solution for addressing the global energy crisis and combating climate change is explored. BPVs harness renewable electricity from sunlight and water through the photosynthetic activity of microorganisms, such as cyanobacteria and algae, serving as living photocatalysts. The focus is primarily on enhancing photocurrent outputs by developing efficient anode materials. Carbon‐based electrodes, particularly graphene (Gr), emerge as promising candidates due to their cost‐effectiveness, electrical conductivity, and mechanical strength. Despite reduced graphene oxide being commonly used, unoxidized Gr has not been extensively explored until recent research demonstrating its excellent current harvesting capacities. Additionally, 1D‐structured nanomaterials, such as electrospun nanofibers, show potential in promoting electron transport and enhancing charge collection efficiency. An innovative photoanode design is introduced, utilizing cyanobacteria immobilized on a cellulose acetate/Gr electrospun mat, offering a porous structure conducive to cyanobacterial attachment and efficient electron transfer. A complementary cathode structure, employing aniline‐modified Pt nanoparticles, facilitates the reduction of protons to yield hydrogen gas. Overall, in this study, BPVs' potential is highlighted as a viable clean energy technology and novel approaches to enhance their efficiency and sustainability are presented. [ABSTRACT FROM AUTHOR]

This study explores the use of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) membranes for pure hydrogen production via water splitting. The membrane was coated with a BaCe0.2Fe0.8O3-δ catalyst to activate the water splitting reaction in a membrane reactor. H2O/Ar and CH4/Ar gas mixtures were supplied to the feed and sweep sides, respectively. Exit gases were analysed in situ using micro-GC. The results revealed that the hydrogen production rate increased with increasing temperature, methane, and water concentrations. The highest hydrogen production rate (0.37 µmol/cm2s) was achieved at 925 °C using 15% CH4 in the sweep and 55% H2O in the feed. On the sweep side, CH4 reacts to generate CO2 and syngas (H2 + CO) in a ratio commonly used in integrated gasification combined cycle power plants. This study highlights the potential of BSCF membranes as a promising technology for simultaneous production of pure hydrogen, on one side, and syngas through controlled reactions involving methane and permeated oxygen, on the other side. [ABSTRACT FROM AUTHOR]

This work is devoted to the analysis of scientific articles in the field of hybrid energy complexes based on hydrogen technologies and renewable energy sources. A special attention is given to wind generation. The review of the topics of scientific publications indexed in the Scopus database in the field of research is carried out, the most frequently encountered topics and the rarest ones are highlighted. Brief statistics about publications selected for detailed analysis are given. The most interesting direction for studying is development of control systems for hybrid energy complexes. Several traditional approaches, which are commonly used in research on this topic and methods are highlighted. The existing shortcomings and inaccuracies in the overviewed works are identified. Conclusions are drawn about the need to transform existing methods and specific proposals are made to improve management systems to increase the efficiency of decision-making and achieve greater economic benefits. Promising areas of research that also require special attention are formulated. [ABSTRACT FROM AUTHOR]

Sustainable hydrogen generation is preferred over production from fossil sources in the context of a carbon‐neutral economy. As a result, production costs for CO2‐based products are estimated to be much higher than those of their fossil equivalents. Hence, it is essential to optimize process chains regarding their hydrogen efficiency. In this study, a concept for the directly coupled production of CO2‐based methanol and formaldehyde in a modified silver catalyst process is evaluated regarding the utilization of H2. Detailed simulations in Aspen Plus allow the comparison to the separately operated synthesis of green methanol and formaldehyde. By directly connecting both production steps, utilization ratios of introduced H2 and CO2 could be improved, reaching values of 98 % and 99 %, respectively. [ABSTRACT FROM AUTHOR]

The development of high-performance and highly stable electrocatalysts is crucial and challenging for the hydrogen evolution reaction (HER). MOFs complexed with SnS2 can form complexes with inserted structures, and their large specific surface area and numerous pores favor mass transfer, exposing the S active sites to more SnS2, improving the utilisation of the active sites and enhancing the catalytic activity for the HER. Structural collapse can be hindered to improve the stability of the HER composites. Herein, six different kinds of SnS2 were synthesized by a hydrothermal method under discrete conditions, and SI8-SnS2 was screened out to have optimal morphology and electrocatalytic performance. Two innovative SnS2@Ni-MOF and SnS2@HKUST-1 as efficient electrocatalysts were synthesized by a facile grinding method for hydrogen generation. SnS2@Ni-MOF and SnS2@HKUST-1 catalysts showed lower overpotentials of 117 mV and 142 mV at 10 mA cm−2 (η10) and smaller Tafel slopes (58 mV dec−1 and 93 mV dec−1) than six different kinds of SnS2, Ni-MOF and HKUST-1 in 0.5 M H2SO4. Meanwhile, the Cdl values for SnS2@Ni-MOF and SnS2@HKUST-1 were estimated to be 11.5 mF cm−2 and 8.0 mF cm−2, and the stabilities of SnS2, Ni-MOF, HKUST-1, SnS2@Ni-MOF, and SnS2@HKUST-1 were tested at a current density of 10 mA cm−2. The current densities of SnS2@Ni-MOF and SnS2@HKUST-1 were stable over 8 h compared to the pure samples, and SEM, XPS tests were run after the HER test, indicating that the materials have excellent electrocatalytic stability. The syntheses of SnS2@Ni-MOF and SnS2@HKUST-1 enhance their intrinsic catalytic activity, and the porous structure promotes mass transfer efficiency, thereby improving the HER performance, which will guide the development of new and promising electrocatalysts for HER. [ABSTRACT FROM AUTHOR]

In response to the rising demand for catalytic hydrogen production, more attention is focused on noble-metal-free catalysts such as cobalt-based metal–organic frameworks (MOFs) and their derivatives. Due to the varying activity of cobalt forms in photocatalytic processes, the present study explores the performance of photo-driven hydrogen generation of cobalt nitrilotriacetate (Co-NTA) with metal ions and MOF-derived carbons containing Co/CoO x /CoN x. The needle-like morphology of the obtained Co-NTA template was preserved in carbon materials prepared through carbonization with and without furfuryl alcohol. Carbons featured nitrogen-containing graphitic structures and oxygen functional groups. They were also characterized by a more developed specific surface area and larger pore volume compared to their parent MOF. All materials evolved hydrogen under visible light in a photosensitized system. Owing to the high content of metallic cobalt on the surface of non-impregnated carbon, it produced three times more hydrogen (14.2 mmol g−1) than Co-NTA. [Display omitted] • Carbonized pure and furfuryl alcohol-impregnated Co-NTA preserved needle shape. • Ionic cobalt in MOF transformed into Co/CoO x /CoN x in carbon materials. • Pyrolized samples revealed N-doped graphitic structures and oxygen functionalities. • Co@carbons photocatalytically generated 3- and 2.5-fold more H 2 than MOF. • Higher activity of carbons was mainly attributed to the metallic cobalt content. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate the economic feasibility of leveraging H 2 generated from biogas for 28 sanitary landfill consortia in the state of Minas Gerais, Brazil. Two processes were analyzed: steam methane reforming (SMR) and pyrolysis reforming. Both were assessed via the economic analyses of Net Present Value (NPV), Levelized Cost of Hydrogen (LCOH) and Internal Rate of Return (IRR). Potential biogas production from sanitary landfills was estimated along with the production of hydrogen and ammonia. Installation (CAPEX) along with operation and maintenance (OPEX) costs were estimated for the biogas purification processes and attainment of H 2. The sales rate for H 2 as a fuel source was derived for each consortium. The capacity for ammonia attainment from H 2 was determined as well as the Levelized Cost of Ammonia (LCOA). The installed capacity of the consortia varied from 18,332.05 to 2,470,525.30 kg H 2 /year. The LCOH varied from 7.01 US$/kg to 44.45 US$/kg. Comparing the three scenarios, the Steam Methane Reforming (SMR) without CO 2 capture obtained the best economic results; however, this scenario leads to the emission of CO 2. The novelty of this research resides in the use of biogas to obtain H 2 and ammonia, as well as in comparing SMR with pyrolysis. The consortium CIDES showed the best economic results. The reformation processes of CH 4 in H 2 with zero CO 2 emissions obtained the best LCOH values, thus making it less competitive in relation to fossil fuels. Public policy changes are necessary to incentivize the production and use of H 2 and ammonia from biogas. • Economic feasibility of leveraging H 2 from biogas for sanitary landfill in Brazil. • Two processes were analyzed: steam methane reforming and pyrolysis reforming. • Biogas production was estimated along with the production of hydrogen and ammonia. • Ammonia attainment from H 2 and the Levelized Cost of Ammonia were determined. • Installed capacity of consortia varied from 12,738.08 to 1,716,651.77 kgH 2 /year. [ABSTRACT FROM AUTHOR]

Graphitic Carbon Nitride (g-C 3 N 4) photocatalyst is considered a prime material for environmental remediation and solar energy conversion application. It drew attention in the field of artificial photosynthesis, i.e. solar fuel (hydrogen) generation via photocatalytic water splitting due to its high chemical and thermal stability, appealing optical properties, low cost, suitable band structure, non-toxicity, easy synthesis, and/or visible light band gap (∼2.7 eV) Herein, this review focuses on the recent advances on g-C 3 N 4 -based materials for efficient solar fuel (Hydrogen) generation via photocatalytic water-splitting, especially synthesis approach, morphological strategies (0D, 1D, 2D, and 3D, g-C 3 N 4)), modification of g-C 3 N 4 including doping strategies and heterostructure formation. Different challenges associated with g-C 3 N 4 , hindering its overall performance are also identified. Also, the recent advancement of g-C 3 N 4 -based materials towards solar fuel (hydrogen) generation application is reviewed. The preparation approach for g-C 3 N 4 , photocatalytic reaction and structural and electronic modification are reviewed. Importantly, the solar H 2 production improvements achieved in the study of the g-C 3 N 4 material as the main photocatalyst have been exclusively reviewed and discussed. Based on the findings in this review, Ti 3 C 2 /N,S-TiO 2 /g-C 3 N 4 is the compound with highest hydrogen production rate of 49506 μmol h−1 g−1, using thermal annealing and ultrasonic assisted impregnation method with H 2 O as the only sacrificial agent. Thus, this review would likely motivate researchers to broaden the applications for g-C 3 N 4 -based materials in solar fuel (hydrogen) generation. • Synthesis approach of g- C 3 N 4 -based material was reviewed and discussed. • Modification strategies of g-C 3 N 4 were discussed in details. • Challenges associated with g-C 3 N 4 , hindering its overall performance are also identified. • The recent advances of g-C 3 N 4 towards hydrogen generation application was reviewed. [ABSTRACT FROM AUTHOR]

The layered double hydroxides (LDHs) of transition metals are of great interest as building blocks for the creation of composite photocatalytic materials for hydrogen production, environmental remediation and other applications. However, the synthesis of most LDHs is reported only by the conventional coprecipitation method, which makes it difficult to control the catalyst's crystallinity. In the present study, ZnCr- and NiCr-LDHs have been successfully prepared using a facile hydrothermal approach. Varying the hydrothermal synthesis conditions allowed us to obtain target products with a controllable crystallite size in the range of 2–26 nm and a specific surface area of 45–83 m2∙g−1. The LDHs synthesized were investigated as photocatalysts of hydrogen generation from aqueous methanol. It was revealed that the photocatalytic activity of ZnCr-LDH samples grows monotonically with the increase in their average crystallite size, while that of NiCr-LDH ones reaches a maximum with intermediate-sized crystallites and then decreases due to the specific surface area reduction. The concentration dependence of the hydrogen evolution activity is generally consistent with the standard Langmuir–Hinshelwood model for heterogeneous catalysis. At a methanol content of 50 mol. %, the rate of hydrogen generation over ZnCr- and NiCr-LDHs reaches 88 and 41 μmol∙h−1∙g−1, respectively. The hydrothermally synthesized LDHs with enhanced crystallinity may be of interest for further fabrication of their nanosheets being promising components of new composite photocatalysts. [ABSTRACT FROM AUTHOR]

In this study, a series of cobalt-based spinel ferrites catalysts, including nickel, cobalt, zinc, and copper ferrites, were synthesized using the sol–gel auto-combustion method followed by a chemical reduction process. These catalysts were employed for accelerating hydrogen generation via the sodium borohydride hydrolysis process. A continuous stirred tank reactor was used to perform catalytic reactor tests. All samples were subjected to analysis using XRD, FESEM, EDX, FTIR, and nitrogen adsorption–desorption techniques. The results revealed that the cobalt-based copper ferrite sample, Co/Cu-Ferrite, exhibited superior particle distribution, and porosity characteristics, as it achieved a high hydrogen generation rate of 2937 mL/min.gcat. In addition, the higher electrical donating property of Cu-Ferrite which leads to the increase in the electron density of the cobalt active sites can account for its superior performance towards hydrolysis of NaBH4. Using the Arrhenius equation and the zero-order reaction calculation, activation energy for the sodium borohydride hydrolysis reaction on the Co/Cu-Ferrite catalyst was determined to be 18.12 kJ/mol. This low activation energy compared to other cobalt-based spinel ferrite catalysts confirms the catalyst's superior performance as well. Additionally, the outcomes from the recycling experiments revealed a gradual decline in the catalyst's performance after each cycle during 4 repetitive cycles. The aforementioned properties render the Co/Cu-Ferrite catalyst an efficient catalyst for hydrogen generation through NaBH4 hydrolysis. [ABSTRACT FROM AUTHOR]

Nanostructured In 2 O 3 was grown on TiO 2 NPs by thermal treatment of the solids mixture of TiO 2 with the parent In(OH) 3. The effect of calcination temperature in the range between 400 °C and 700 °C was investigated and peculiar changes both in the structure and in the catalytic activity of the TiO 2 /In 2 O 3 heterostructure were revealed. It was found out that T = 600 °C is the best operating temperature for hydrogen production and in combination with 3.5 wt% In 2 O 3 the H 2 production from water reached the value of 3.5 mmol/h.g irradiating in the UV–Vis region. Once 5.0 wt% Cu 2 O nanoparticles were loaded on TiO 2 /In 2 O 3 , the photocatalytic activity boosted to 9.6 mmol/h.g of H 2 , overcoming the hydrogen production of pristine TiO 2 by a factor of 48. This result can be attributed to the formation of a highly efficient heterojunction that assures a synergistic cooperation among the three semiconductors yielding an improved charge separation and faster charge transport, as evidenced by Mott-Schottky, PL and EIS measures. [Display omitted] • Thermal annealing of the mixture TiO 2 /In(OH) 3 was studied at different temperatures. • Improved HER activity for TiO 2 /In 2 O 3 annealed at T = 600 °C was observed. • A double carrier density and a reduced resistivity were measured for calcined TiO 2 /In 2 O 3. • Integration of Cu 2 O boosted the photocatalytic activity 48-folds respect to TiO 2. [ABSTRACT FROM AUTHOR]

Carbon nitride (C3N4) has gained considerable attention and has been regarded as an ideal candidate for photocatalytic hydrogen evolution. However, its photocatalytic efficiency is still unsatisfactory due to the rapid recombination rate of photo-generated carriers and restricted surface area with few active sites. Herein, we successfully synthesized a single-atom Pt cocatalyst-loaded photocatalyst by utilizing the anchoring effect of carbon dots (CDs) on C3N4. The introduction of CDs onto the porous C3N4 matrix can greatly enhance the specific surface area of C3N4 to provide more surface-active sites, increase light absorption capabilities, as well as improve the charge separation efficiency. Notably, the functional groups of CDs can efficiently anchor the single-atom Pt, thus improving the atomic utilization efficiency of Pt cocatalysts. A strong interaction is formed via the connection of Pt-N bonds, which enhances the efficiency of photogenerated electron separation. This unique structure remarkably improves its H2 evolution performance under visible light irradiation with a rate of 15.09 mmol h−1 g−1. This work provides a new approach to constructing efficient photocatalysts by using CDs for sustainable hydrogen generation, offering a practical approach to utilizing solar energy for clean fuel production. [ABSTRACT FROM AUTHOR]