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The hybrid drive wind turbine (WT) can be friendly connected to the power grid by using a speed regulating differential mechanism (SRDM) instead of partially or fully rated converters, which has been considered as a promising solution for the stable consumption of large-scale wind power generation. To further improve the on-grid performance of hybrid drive WTs, this paper develops a multi-source power generation scheme, in which a hydrogen storage system (HSS) is integrated for mitigating the wind power generation intermittencies. The overall architecture and kinematic principles of the proposed wind–hydrogen generation system, called SRDM-based WT with HSS, are first analyzed. Then, the graphical descriptions of mathematical models are finalized via the Energetic Macroscopic Representation method, by which the physical characteristics and energy flow relationships are revealed. To ensure the economical and stable operation of the proposed wind–hydrogen scheme, an effective optimal allocation framework, considering the uncertainties from wind power output and load demand, is presented to HSS, targeting the maximum annual revenue. The effects of several key HSS parameters on the capacity allocation results are also investigated. Moreover, aiming at the different system working modes, an energy management approach is synthesized to achieve the interaction analysis and power supervision between energy sources and storage elements. Finally, experimental and simulation case studies are demonstrated. Results illustrate the effectiveness of the proposed approaches and the optimal performance for uninterrupted on-grid operation of the proposed wind–hydrogen energy system. [ABSTRACT FROM AUTHOR]

Strontium titanate (SrTiO3) with a perovskite structure is widely applied to hydrogen production by photolysis water splitting. However, the existing preparation techniques cannot make uniform high-purity strontium titanate without causing pollution under simple conditions. Therefore, a preparation technique that can mass-produce uniform high-purity and environmentally friendly strontium titanate at low temperatures is particularly important. In this paper, a sol–gel method is used to coat strontium carbonate with a TiO2 precursor. The core–shell structure formed by this structure increases the contact area between the reactants, which is beneficial to the diffusion between elements and promotes the kinetic process of the reaction, and pure-phase nano-strontium titanate can be made at low temperatures. The microstructure of the samples before and after calcination at 800 °C is analyzed by FT-IR. The chemical composition and the valence state of the calcined samples at 800 °C are analyzed by XPS. The structure of the samples at different heat treatment temperatures is observed and the structure of the samples at the same heat treatment temperatures with different heat treatment times is observed by XRD and transmission electron microscopy. TGA-DSC is used to monitor the changes in mass and heat during the reaction. The transformation mechanism and nucleation process of the material are analyzed from the perspective of thermodynamics and kinetics. In addition, the UV-visible absorption spectrum is used to calculate the forbidden band width. Finally, the activity of the hydrogen produced by water-splitting the sample under different heat treatment conditions is measured. The results showed that strontium titanate was produced at the contact interface at 600 °C, and the pure phase of strontium titanate was produced at 800 °C with a size of 34 nm. The reaction process conforms to the nucleation-growth model and the grain grows with the driving force of grain boundary and the temperature increase. The forbidden band width of the pure-phase strontium titanate produced after calcination at 800 °C is 3.173 eV, with the best photocatalytic performance, and its hydrogen production rate is 2.40 μmol g−1 mol−1. This work provides a new preparation process for nano-strontium titanate and may be highly applied to hydrogen production by photolysis water splitting. [ABSTRACT FROM AUTHOR]

Metal halide perovskites, such as iodine methylamine lead (MAPbI3), have received extensive attention in the field of photocatalytic decomposition of HI for hydrogen evolution, due to their excellent photoelectric properties. In this paper, a new MAPbI3-based composite, MoC/MAPbI3, was synthesized. The results show that 15 wt% MoC/MAPbI3 has the best hydrogen production performance (38.4 μmol h−1), which is approximately 24-times that of pure MAPbI3 (1.61 μmol h−1). With the extension of the catalytic time, the hydrogen production rate of MoC/MAPbI3 reached 165.3 μmol h−1 after 16 h due to the effective separation and transfer of charge carriers between MoC and MAPbI3, showing excellent hydrogen evolution rate performance under visible light. In addition, the cycling stability of MoC/MAPbI3 did not decrease in multiple 4 h cycle tests. This study used the non-precious metal promoter MoC to modify MAPbI3, and provides a new idea for the synthesis of efficient MAPbI3-based composite catalysts. [ABSTRACT FROM AUTHOR]

N-rich precursors govern the thermal polymerization formation of graphitic carbon nitride (g-C 3 N 4) based catalysts towards enhanced photocatalytic performance. In this paper, Cu components were introduced in superior thin g-C 3 N 4 nanosheets using the thermal polymerization copper acetate and bulk g-C 3 N 4 created by different precursors including melamine, dicyandiamide, and thiourea, such as melamine-g-C 3 N 4 (MCN), dicyandiamide-g-C 3 N 4 (DCN), and thiourea-g-C 3 N 4 (TCN). The performance of Cu-g-C 3 N 4 nanosheets depended strongly on the precursors of bulk g-C 3 N 4 samples. The well-developed Cu nanoparticles with clear lattice fringes were observed in the sample prepared using MCN (sample Cu-MCN) while the crystallinity of Cu nanoparticles became worse in the sample prepared using DCN (sample Cu-DCN). Interestingly, Cu clusters were homogeneously distributed in superior thin g-C 3 N 4 nanosheets in the case of using TCN (sample Cu-TCN) because of S components in thiourea affected the thermal polymerization. The photocatalytic activity of Cu-TCN was drastically improved compared with other Cu-g-C 3 N 4 samples. The photocatalytic hydrogen production rate of Cu-TCN with 1% of Cu components was 4035.6 μmol g-1 h-1. Cycle stability test indicated that sample Cu-TCN revealed high stability, in which the H 2 generation rate was retained 95% of their initial value after 5 cycles. These results supply efficient approaches for the study and application of g-C 3 N 4 based photocatalysts. • Cu components introduced in g-C 3 N 4 nanosheets using bulk g-C 3 N 4 created by different precursors. • Precursors (melamine, dicyandiamide, and thiourea) affect the activity of Cu-g-C 3 N 4 nanosheets. • Cu distribution in g-C 3 N 4 nanosheets depended on the thermal polymerization of precursors. • Cu clusters distributed in g-C 3 N 4 nanosheets created using thiourea revealed the best performance. [ABSTRACT FROM AUTHOR]

Developing highly active and stable non-noble-metal cocatalyst-decorated semiconductors is desirable for the practical application of photocatalysis, which remains an open question. Herein, we report transition-metal nitride (Ni3FeN) loaded cadmium sulfide (CdS) nanorods prepared through a simple hydrothermal method and surface treatment with NH3. The as-prepared photocatalyst Ni3FeN (3 wt%)/CdS showed a hydrogen evolution rate of 4.6 mmol g−1 h−1, which was 23.8 and 6.8 fold higher than those of CdS and Pt (1 wt%)/CdS, respectively. The Ni3FeN/CdS sample exhibited remarkable stability for seven consecutive cycles of photocatalytic tests lasting 21 hours. It was confirmed through Kelvin probe measurements that a Schottky junction between Ni3FeN and CdS gave rise to the inhibited recombination of photogenerated carriers, which benefited the photocatalytic HER performance. [ABSTRACT FROM AUTHOR]

Present paper aims to investigate effects of nanoparticle addition to thermal oil of parabolic trough collectors which are integrated to Kalina cycle for electricity generation to run an alkaline electrolyzer for hydrogen production. Thermodynamic models for Kalina cycle, thermal model for parabolic collectors and electrochemical models for water electrolyzer are developed for overall plant modeling. Three types of nanoparticles including: copper oxide, alumina and titanium oxide are considered and overall plant performance is investigated using these nanoparticles and is compared with basefluid. The nanofluid thermophysical properties are evaluated as a function of nanoparticles' properties, volume fraction and the base fluid properties. The effects of key variables such as nanoparticle volume fraction, collector inlet temperature, evaporation pressure and ammonia concentration of Kalina system were evaluated on hydrogen production as well as exergetic efficiencies. Results revealed greater positive influence for CuO compared to TiO 2 and Al 2 O 3 on performance improvement for both hydrogen generation and its exergetic efficiency. Also, compared to basefluid (without nanoparticles) case, it was found that CuO particles result in a solar-to-H 2 exergy efficiency improvement by 4.7%. Using this nanofluid with a volume fraction of 5%, the H 2 production rate enhances from 0.633 kg / h to 0.664 kg / h , indicating 4.9 % improvement. • An alkaline electrolyzer-based hydrogen production plant powered by PTC is modeled. • Three types of nanoparticles are employed for hydrogen production enhancement. • Copper oxide nanoparticles are found to be better than titanium oxide and alumina. • Nanoparticles are applied to enhance the PTC thermal performance. • Hydrogen production rate can be enhanced by 4.9 % using CuO nanoparticles. [ABSTRACT FROM AUTHOR]

This study developed an efficient photocatalyst for hydrogen production, consisting of CdS nanorods and the CoTPPBr4 co-catalyst. The synthesized photocatalyst was characterized using a suite of techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Additionally, transient photocurrent response and electrochemical impedance spectroscopy (EIS) were carried out to further probe the material's properties. Our findings demonstrate that the CoTPPBr4 co-catalyst significantly enhances the photocatalytic H2 evolution efficiency under visible light irradiation. Notably, among the tested photocatalysts, a 12.5% CoTPPBr4/CdS composite exhibited the most superior photocatalytic performance, achieving a hydrogen production rate of 41.3 mmol g−1 h−1, which is 4.1 times higher than that of pristine CdS. The introduction of CoTPPBr4 effectively facilitates charge transfer within CdS, enhances the separation efficiency of light-induced electron–hole pairs, and boosts the surface H2-evolution kinetics. This research not only introduces a promising photocatalyst for visible light-driven hydrogen production but also provides a way for the development of highly efficient and stable CdS-based hybrid semiconductor nanocomposites suitable for diverse photocatalytic applications. [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]

Designing cost-effective catalysts with the structural features and necessary functionality to drive ammonia borane hydrolysis for hydrogen generation remains a challenge. In this work, a close heterojunction of Fe3O4--Ni2P uniformly embedded in amorphous carbon material (Fe3O4--Ni2P@C) has been prepared via surface phosphorization. The catalyst displays superior activity with a turnover frequency (TOF) of 92.8 min-1 and favorable durability for ammonia borane hydrolysis, making it superior to most reported nickel-based catalysts. The theoretical studies show a high electron density on the Fe3O4--Ni2P heterojunction. Combining the theoretical and experimental results, the dual active sites at the heterojunction are beneficial to the adsorption of reactant molecules and the reduction of the reaction barrier. This strategy of constructing an appropriate heterojunction to maximize synergistic effects may open a new avenue for non-precious metal catalysis. [ABSTRACT FROM AUTHOR]

Hydrogen gas is a prominent focus in pursuing renewable and clean alternative energy sources. The quest for maximizing hydrogen production yield involves the exploration of an ideal photocatalyst and the development of a simple, cost‐effective technique for its generation. Iron titanate has garnered attention in this context due to its photocatalytic properties, affordability, and non‐toxic nature. Over the years, different synthesis routes, different morphologies, and some modifications of iron titanate have been carried out to improve its photocatalytic performance by enhancing light absorption in the visible region, boosting charge carrier transfer, and decreasing recombination of electrons and holes. The use of iron titanate photocatalyst for hydrogen evolution reaction has seen an upward trend in recent times, and based on available findings, more can be done to improve the performance. This review paper provides a comprehensive overview of the fundamental principles of photocatalysis for hydrogen generation, encompassing the synthesis, morphology, and application of iron titanate‐based photocatalysts. The discussion delves into the limitations of current methodologies and present and future perspectives for advancing iron titanate photocatalysts. By addressing these limitations and contemplating future directions, the aim is to enhance the properties of materials fabricated for photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

Proton exchange membrane (PEM) electrolyzers are promising devices for hydrogen production from water splitting, but their performance and stability are still limited by various factors. This paper studies the effects of different structures on the performance of PEM electrolyzers, focusing on the working temperature, water conductivity, and the structure of bipolar plate. The results show that higher temperature and lower water conductivity enhance the electrolyzer performance, by increasing the catalyst activity and the proton transport. Moreover, a novel structure using a platinum-coated titanium mesh-based bipolar plate is proposed and tested. This structure improves the performance of the electrolyzer, by optimizing the mass transport, pressure drop, and water management in the electrolyzer. A 23-cell electrolyzer with this structure is developed and demonstrated. The electrolyzer achieves a high performance and stability, with a cell voltage of 1.742 V, a voltage efficiency of 85.0%, and a hydrogen production rate of 1.14 Nm3/h at 0.99 A/cm2. The observed cell voltage for the PEM electrolyzer is consistent with the documented range, typically spanning from 1.55 to 1.90 V at a current density of 0.99 A/cm2. This suggests that our bipolar plate design simplifies PEM electrolyzer manufacture while maintaining comparable performance to existing electrolyzers. [Display omitted] • Performance of PEM electrolyzers affected by different structures. • Higher temperature and lower water conductivity enhance performance. • Platinum-coated titanium mesh as flow field plate improves performance. • 23-cell electrolyzer with novel structure achieves high performance and stability. [ABSTRACT FROM AUTHOR]

The designing of efficient electrocatalysts for hydrogen generation is essential for the practical application of water-splitting devices. With numerous electrochemical advantages, transition metal sulphides are regarded as the most promising candidates for catalysing the hydrogen evolution reaction (HER) in acidic media. In the present study, Ru-doped cobalt sulphide nanosheets, termed Co9S8/Ru@t (t = 24 h, 48 h, and 72 h), were obtained by varying the reaction time from 24 h to 72 h from a RuCo-PBA precursor. The role of the time period for the synthesis of Co9S8/Ru@48h is vital in increasing the number of electroactive sites and optimising the hydrogen adsorption–desorption phenomena leading to an increment in the HER activity. The electrochemical outcomes demonstrate that the optimized Co9S8/Ru@48h requires a low overpotential of just 94 mV to produce 10 mA cm−2 current density, and also exhibits a lower Tafel slope value of 84 mV dec−1 defining its faster reaction kinetics. The as-synthesized Co9S8/Ru@48h was stable for up to 20 h of constant electrolysis signifying its outstanding durability. The optimized synthetic approach and impressive electrochemical results make Co9S8/Ru@48h a suitable alternative to noble-metal-based electrocatalysts for the HER. [ABSTRACT FROM AUTHOR]

A dedicated grid-tied offshore hybrid energy system for hydrogen production is a promising solution to unlock the full benefit of offshore wind and solar energy and realize decarbonization and sustainable energy security targets in electricity and other sectors. Current knowledge of these offshore hybrid systems is limited, particularly in the integration, component control, and allocation aspects. Therefore, a grid-integrated analytical model with a power dispatch allocation strategy between the grid and electrolyzer for the co-production of hydrogen from the offshore hybrid energy system is developed in this paper. While producing hydrogen, the proposed offshore hybrid energy system supplies a percentage of its capacity to the onshore grid facility, and the amount of the electricity is quantified based on the electricity market price and available total offshore generation. The detailed controls of each component are discussed. A case study considers a hypothetical hybrid offshore energy system of 10 MW situated in a potential offshore off the NSW of Australia based on realistic metrological data. A grid-scale proton-exchange membrane electrolyzer stack is used and a model predictive power controller is implemented on the distributed hydrogen generation scheme. The model is helpful for the assessment or optimization of both the economics and feasibility of the dedicated offshore hybrid energy farm for hydrogen production systems. • Modeling of a grid-integrated analytical model of an OHES for hydrogen co-production. • Development of a power dispatch allocation strategy for the proposed OHES. • Development of detailed controls of each component used in the proposed OHES. • Demonstrations of a case study considering 10 MW OHES situated in offshore off the NSW of Australia. [ABSTRACT FROM AUTHOR]

This comprehensive review delves into the utilization of ultrasound for hydrogen generation, emphasizing the key mechanisms and techniques involved. One of the focal points of the study is the exploration of the generation and detection of cavitation bubbles, which are induced by ultrasound waves. An in-depth overview of various experimental setups that employ ultrasound technology for hydrogen production is also provided. A comparative analysis of these setups reveals differences in crucial parameters such as acoustic intensity, liquid temperature, and frequency. These are the key parameters identified as significant determinants affecting the hydrogen yield and efficiency. This review paper also highlights the potential applications of sonohydrogen as a viable energy resource. While challenges such as the high costs of ultrasound equipment and the need for efficient catalysts exist, the inherent benefits make sonohydrogen a compelling subject for future research and development. The study shows that there is no one-size-fits-all approach, accentuating the importance of understanding these parameters for optimizing the process of hydrogen production. Although the technology is primarily in the experimental phase, existing research indicates that the sonohydrogen production holds considerable potential for large-scale applications. [Display omitted] • The study explores ultrasound's role in enhancing hydrogen production. • The article reviews various experimental setups and comparing them. • The manuscript identifies key parameters affecting sonohydrogen production. • The study discusses the potential dimensions of sonohydrogen options and future research directions. • It examines scaling sonohydrogen production challenges for industrial use. [ABSTRACT FROM AUTHOR]

Water-splitting coupled with the hydrazine oxidation reaction (HzOR) is a remarkably important strategy for H2 production, but remains a challenge. Herein, a Fe-doped Ni2P-Co2P-Zn3P2 heterogeneous electrocatalyst with a nanoneedle-assembled nanosphere structure and abundant defects was fabricated on Ni foam (Fe-NiCoZnP/NF). The introduction of Fe can tune the electron structure of NiCoZnP/NF, leading to a modulation of the d-band center towards the Fermi level, hence optimizing the free energy of hydrogen (ΔGH*) and dehydrogenation behavior of hydrazine, and thereby realizing splendid HER and HzOR activities. The fabricated Fe-NiCoZnP/NF catalyst displays outstanding HER and HzOR activity and durability, with potentials of 121 and 13 mV vs. RHE to drive 1000 mA cm-2 and Tafel slopes of 31.2 and 11.9 mV dec-1, respectively, and a long durability of 120 h to achieve 100 mA cm-2. Impressively, overall water-hydrazine electrolysis employing Fe-NiCoZnP/NF as the anodic and cathodic electrodes only requires low voltages of 1.92 and 2.67 V to achieve 100 and 1000 mA cm-2, respectively, with a high stability for 120 h operation time during overall hydrazine splitting (OHzS). This work offers a justification for the design of high-efficiency bifunctional catalysts, and promotes energy-saving industry-level hydrogen generation. [ABSTRACT FROM AUTHOR]

The hydrogen production from natural gas has advantages of low investment, low carbon emission, and high hydrogen production rate. This paper briefly describes the technical overview of hydrogen production from natural gas reforming and identifies its risk factors. According to the dangerous characteristics of high reaction temperature, easy leakage of reaction medium, flammability, and explosion in the process, the intrinsic safety of the process is discussed in combination with relevant research and industrial experience. The safety requirements of key equipment and materials are introduced in detail, followed by the optimization methods of process safety that can be taken in the engineering process. Besides, the accident prevention measures for emergency shutdown and fire explosion are summarized. Finally, the future research demands are put forward from the perspective of research and development, which is instructive for the safe hydrogen production from natural gas in the future. [ABSTRACT FROM AUTHOR]

In the photocatalytic processes of ferroelectric semiconductor materials, how to induce a depolarized electric field (Edp) by polarization to reduce the electron–hole recombination rate is still a big problem. Here, the ABO3-type K0.5Na0.5NbO3 (KNN) material is modified by Nd and Ni elements at A/B sites to narrow the band gap and maintain the room-temperature ferroelectric behavior. The 0.96KNN–0.04NdNiO3 sample shows the narrowed band gap (∼2.75 eV) and high residual polarization value (∼11.56 μC cm−2). After high-field poling, the hydrogen production rate of the sample in the full spectrum reaches 926.28 μmol g−1 h−1, indicating an increase of approximately 5 times compared to the 170.45 μmol g−1 h−1 of the unpoled sample. The improved performance of photocatalytic hydrogen production mainly results from the reduction of band gap and the formation of Edp after polarization. The change in the position of the top of the valence band after sample polarization reveals that high-field poling can improve charge transport efficiency by energy band bending. [ABSTRACT FROM AUTHOR]

Renewable hydrogen is considered as one of the key technologies that may be needed to fully decarbonise our economies, providing the high-temperature heat, fuels and feedstock that might not be possible to electrify. Several pilot projects are underway, and some assessments of the economics of green hydrogen have been published. However, most of them have assessed the costs of producing renewable hydrogen in large-scale, grid-connected units. Another option, pointed by many as a robust strategy in the early stages, is to produce hydrogen locally, in "hydrogen valleys", to serve industrial demand. In this paper, the economics of the different technical configurations and strategies that might be used for this decentralised, variable-demand option are analysed, accounting for the impact that a non-constant operation may cause on the operational efficiency of electrolysers, and for the potential benefits of local hydrogen storage. Our results show that when hydrogen demand is variable, production costs are higher compared to the constant demand case, due to the higher electrolyser size required. Electricity price optimization plus hydrogen storage can be a valuable option in some cases, although the cost benefit is negligible (about 1%) unless price volatility in the market increases with higher RES shares, or investment costs decrease significantly. Sourcing electricity exclusively from a dedicated renewable power plant can only become competitive if electricity market prices rise as observed recently or triggered by increasing CO 2 prices. • Different production strategies are compared to minimise H 2 production costs. • Faraday efficiency increases costs for variable electricity generation. • Electricity price optimization is best for H2 valleys, although compression costs may change this. • Direct H 2 production from renewable plants is not competitive with current prices. [ABSTRACT FROM AUTHOR]

Hydrogen is a great energy carrier that has the potential to reduce pollution and greenhouse emissions if produced by renewables and clean energy systems. However, moving from dependence on fossil fuels to renewables without emissions is a giant and challenging leap. Therefore, nuclear energy is a well-established technology that can help cut emissions and produce the electricity required for hydrogen production. Electrolysis is a promising technology that uses electricity to produce hydrogen from water. This paper investigates the integration of a large-scale PEM electrolysis with the APR1400 nuclear power plant to produce hydrogen. The two subsystems are, firstly, separately modeled using energy and exergy concepts to conduct parametric analysis on each individually. These subsystems are then integrated into one system to evaluate the system performance, hydrogen production rate, and overall system efficiency. The integrated system is examined with different operation conditions. It is found that the overall thermal-to-hydrogen energy and exergy efficiencies of the integrated system are 22.9% and 53.52%, respectively, and the hydrogen production rate is 7.544 kg/s; this makes 651 t per day and 19.5 kt per month. • An APR1400 plant is integrated with a PEM electrolyzer for hydrogen production. • The thermodynamic performance of the integrated system is parametrically analyzed. • The integrated system can produce hydrogen at an optimum exergy efficiency of 53.5%. • The integrated system produces 651 t of H2/day at an energy efficiency of about 23%. [ABSTRACT FROM AUTHOR]

This paper aims to study the feasibility of municipal sewage sludge utilization as an energy source in a polygeneration system. This system offers distinctive benefits such as contribution to the principled removal of sewage sludge, simultaneous utilization of raw and digested sludge in different parts of the system, and production of renewable hydrogen from bio-waste. 4E (energy, exergy, exergoeconomic, and environmental) analyses, are performed to understand the system performance comprehensively. Then, parametric studies are examined the impact of changing the values of main parameters on the system operation. Afterward, a multi-objective optimization based on a genetic algorithm is carried out to achieve optimal values, considering a trade-off between the exergy efficiency and the total cost rate. Meanwhile, this work harnesses the potential of artificial neural networks to expedite complex and time-consuming optimization processes. According to the results, the gasifier exhibits the highest rate of exergy destruction, and the primary cost of consumption is attributed to its heat supply. The multi-objective optimization findings show that the optimum point has an exergy efficiency of 38.26 % and a total cost rate of 58.17 M$/year. The hydrogen production rate, energy efficiency, and net power generation rate for the optimal case are determined as 1692 kg/h, 35.24 %, and 4269 kW, respectively. Also, the unit cost of hydrogen in the optimal case is obtained 1.49 $/kg which offers a cost-effective solution for hydrogen production. [Display omitted] • 4E analysis and optimization performed on a bio-waste driven polygeneration system. • Plant optimized using artificial neural network and multi-objective genetic algorithm. • The feasibility of integrating a membrane for hydrogen separation investigated. • The optimum exergy efficiency and total cost rate obtained 38.26 % and 58.17 M$/year. • Hydrogen and electricity cost of 1.49 $/kg and 0.0145 $/kWh achieved for optimal case. [ABSTRACT FROM AUTHOR]

Visible-light-driven hydrogen evolution from water represents a green and sustainable technology to convert solar energy into chemical energy. Covalent organic frameworks (COFs) are the most competitive platforms among the variety of photocatalysts. Herein, a novel benzotrifuran-based donor–acceptor material (COF-JLU42) was constructed using a Schiff base polycondensation reaction by introducing electron-rich benzotrifuran and deficient triazine moieties into the framework. The new COF features high crystallinity and permanent porosity with a large surface area and proves to be a photoactive semiconductor with efficient visible-light harvesting capacity. Importantly, COF-JLU42 exhibits a superior photocatalytic activity with a hydrogen evolution rate of over 40 000 μmol g−1 h−1 under visible-light illumination, which is 2.5 times higher than that of the isomorphic benzotrithiophene-based COFs under the same conditions. These findings suggest the huge application prospect of benzotrifuran-based framework materials as metal-free and solid photocatalysts in solar-energy conversion and storage. [ABSTRACT FROM AUTHOR]

Improving the separation efficiency of photo-generated electron–hole pair is a key issue in the field of photocatalytic hydrogen production. In this work, we successfully improved the efficiency of photo-generated carrier separation using the synergistic action of sulfur (S) vacancies and a Ni2P co-catalyst. Vs-Zn0.5Cd0.5S (Vs-ZCS) with S vacancies was designed and constructed, and Vs-ZCS/Ni2P photocatalysts were prepared with non-precious metal Ni2P as a co-catalyst. Among all the produced materials, Vs-ZCS/Ni2P-5% has a photocatalytic characteristic of 40.81 mmol g−1 h−1, which is 7.88, 3.08 and 3.75 times greater than those of ZCS (5.18 mmol g−1 h−1), Vs-ZCS (13.25 mmol g−1 h−1) and ZCS/Ni2P-5% (10.88 mmol g−1 h−1), respectively. The results of transient photo-current, electrochemical impedance spectroscopy, photoluminescence and time-resolved fluorescence show that the synergistic effect of S vacancies and Ni2P significantly promotes the separation and transfer efficiency of photo-generated carriers, as well as the photocatalytic hydrogen production reaction. Superoxide radicals and electrons are the active species for photocatalytic hydrogen generation, which is confirmed by active species capture tests and EPR. This study presents an innovative approach for developing photocatalysts with low cost and good catalytic performance. [ABSTRACT FROM AUTHOR]

In the wake of the devastating consequences of climate change, many countries are searching for alternative renewable energy. Hydrogen, the most abundant element on earth, is an alternative clean and non-toxic energy source. Palladium-based membranes and their alloys are categorized as inorganic metallic membranes with the highest selectivity and permeation rate for hydrogen production. Pd-based membranes have great potential for resolving environmental concerns and adverse side effects of greenhouse gases resulting from industrial processes. This paper analyses Pd-based membranes and their industrial applications while focusing on natural gas and methane as non-renewable feedstocks for hydrogen production. Steam reforming of natural gas and methane, partial oxidation reaction, auto thermal reforming, dry reforming, and gas to liquid process are among the processes that take place in a Pd-based membrane reactor and are discussed in this paper. Finally, all the ongoing research and development on both laboratory and industrial scales are reviewed. • The role of hydrogen as a sustainable and alternative energy vector is highlighted. • The use of Pd membrane and its alloys for methane and natural gas reforming processes is discussed. • The mainstream approaches to the production of hydrogen from methane and natural gas are reviewed. • The current industrial applications of palladium membrane reactors are presented. [ABSTRACT FROM AUTHOR]

Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass waste valorization. The process could be scaled up to obtain hydrogen under natural sunlight irradiation, and research on polymeric carbon nitride (g-C3N4)-based photocatalysts has been widely carried out in recent years. The non-metallic-based carbon nitride materials are economical and (photo)stable polymer semiconductors, and their physicochemical surface and electronic properties are optimal for obtaining H2, which can be considered a gas that does not cause major environmental problems. Some hindrances related to their structure, such as the low absorption of visible light and the relatively high recombination rate of electron-hole pairs, restrict the performance; therefore, it is necessary to improve their activity and the yield of the reaction by modifying them in various ways. Various types of solutions have been proposed in this regard, such as, for example, their coupling with other semiconductors to form composite materials. The current mini-review aims to overview the PR field, reporting some of the most interesting papers devoted to understanding the role of g-C3N4 in biomass PR. Information on many physico-chemical aspects related to the performance of the process and possible ways to obtain better results than those present up to now in the literature will be reported. [ABSTRACT FROM AUTHOR]

Fundamental transformations are taking place in the areas of energy structure on the supply side and on the energy-consumption side towards clean, low-carbon and safe energy. Furthermore, a new energy system is being constructed with renewable energy as its core in China with energy transition and 'carbon peak and carbon neutral' as the overall goal. China's hydrogen-industry plan, 'Mid-to-long term hydrogen industry development plan (2021–2035)', has an emphasis on hydrogen generation by using renewable energies as the centre piece, which points in the right direction for hydrogen's green development. In this paper, the current status of China's hydrogen industry is analysed; strategic needs for green hydrogen's development and its hurdles in its paths are sorted out. Integrated demonstration at provincial levels, development of a 'great hydrogen base' and the green-hydrogen development path by gradual substitution with renewable hydrogen are proposed. Scaled-up hydrogen production, expanded consumer hydrogen usage and established hydrogen commodity exchange are recommended to safeguard its development and promote its high-quality development in China. [ABSTRACT FROM AUTHOR]

A highly efficient electrode material is required to explore and apply to microbial electrolysis cell (MEC) with high hydrogen evolution reaction (HER) efficiency. Pt/C was one of the most efficient catalysts for hydrogen production in current lab research, but it was expensive and some chemicals in wastewater were prone to Pt poisoning, which was a great limitation in application. Thus, a cheap and effective nickel(II) Oxide/Y (NiO/Y) material was prepared by using Y zeolites as carrier loaded with NiO in this study, which was used in MEC to evaluate the hydrogen evolution performance in comparison with Pt/C. The results indicated that NiO/Y composites showed a competitive HER performance to Pt/C. The linear sweep voltammetry (LSV) tests and Tafel plots showed that the NiO/Y composites exhibited the best catalytic activity for HER. In the MEC tests, the NiO/Y composites cathode was comparable with the Pt/C cathode in terms of current densities and energy efficiency. The coulombic efficiency, cathodic energy efficiency rate and hydrogen production rate obtained with NiO/Y cathode MEC was 85.88 ± 6.5%, 228.39 ± 3.2% and 0.83 ± 0.05 m3/m3d under, respectively, which were slightly higher than those obtained with the Pt/C cathode MEC. It was concluded that even with the cheap Y zeolites as the supports, the NiO/Y materials showed the superior performance, which was attributed to a good dispersing of the active component of NiO on the large specific surface area of Y zeolites and the fast escape of hydrogen bubbles from microporous and mesoporous structure of Y zeolites. [ABSTRACT FROM AUTHOR]

The photo-fermentative biohydrogen production using photosynthetic purple non-sulfur and non-oxygenic bacteria Rhodobacter sphaeroides is a very promising green technology. In this paper, several strategies conducted in the literature to make the bioprocess more economical, less expensive and more efficient have been reviewed. The used of co-cultures and genetic modification strategies increased the yield and the rate of hydrogen production. Also, the biohydrogen production using organic wastes as a substrate, an environmentally friendly process, in several reactors designs with immobilized and suspension cultures have been employed to achieve a high conversion efficiency of the substrate and light energy. At the optimized conditions, the hydrogen production enhances and becomes more economic. [ABSTRACT FROM AUTHOR]

In this paper, a new Newton-based extremum-seeking control for dynamic systems is proposed using Kalman filter for gradient and Hessian estimation as well as a stochastic perturbation signal with time-varying amplitude. The obtained Kalman filter based Newton extremum-seeking control (KFNESC) makes it possible to accelerate the convergence to the extremum and attenuate the steady-state oscillations. The convergence and oscillation attenuation properties of the closed-loop system with KFNESC are considered, and the proposed control is applied to a two-stages anaerobic digestion process in order to maximize the hydrogen production rate, which has better robustness and a slower steady-state oscillation with the comparison of Newton-based ESC and sliding mode ESC. [ABSTRACT FROM AUTHOR]

In this paper, the results of an experimental study on hydrogen production at a tungsten discharge electrode with negative polarity in the DC electrolysis of a typical 10 wt% Na2CO3 aqueous solution in three operational regimes (the Faradaic, transition, and plasma-driven solution electrolysis (PDSE)) are presented for the first time. To focus the study on hydrogen production, a flowing inert gas (argon) was used to transport the gas mixture produced at the discharge electrode and prevent any other potential chemical reactions. The results showed that the highest hydrogen production rate of 0.147 g(H2)/h was achieved in the cathodic PDSE regime at the applied DC voltage of 198 V. However, the energy yield of hydrogen production of 0.405 g(H2)/kWh obtained at the applied voltage range of 141–170 V in the PDSE regime was lower than that obtained in the Faradaic regime (0.867 g(H2)/kWh) at 28 V. The energy balance of hydrogen production in the cathodic PDSE regime for the typical aqueous solution of Na2CO3 carried out for the first time showed that a significant share (˃98%) of the electrical energy consumed is spent on heating and evaporation of the electrolytic solution. This explains why the energy yield of hydrogen production is low in the PDSE regime. Because most of the energy is consumed for heat generation in the cathodic PDSE regime, organic liquid hydrogen carriers, such as alcohols, which have a lower boiling temperature, heat of evaporation, and standard Gibbs free energy, should be considered better aqueous electrolytic solutions in terms of the energy yield of hydrogen production in the PDSE regime. [ABSTRACT FROM AUTHOR]

The reaction of aluminum water to produce hydrogen is prevented by an alumina film. To prepare a kind of aluminum alloy with instant hydrogen production and high hydrogen yield, this paper investigates the effect of different Ga content and In–Sn ratio on the hydrogen production performance of aluminum alloy, and also observes the effect of hydrogen production at different temperatures. The composition, structure, and thermal properties are observed by Scanning Electron Microscope, X-ray diffraction, and differential scanning calorimetry. With different ratios of In and Sn, they appear as two intermetallic compounds, In 3 Sn and InSn 4. When Ga, In, and Sn were added to aluminum together, the hydrolytic properties of the Al-Ga-In-Sn alloys are greatly improved. The paper finally prepared an aluminum alloy with a hydrogen conversion rate of more than 98% and activation energy of 39.2 kJ/mol. Further the development and utilization of hydrogen energy are promoted. [Display omitted] • A high hydrogen yielding aluminum alloy prepared by melting was proposed. • The hydrolysis rate is proportional to the reaction temperature. • Effect of Ga content and In–Sn ratio on hydrogen production performance. • Effect of low melting point elements on the activation energy of aluminum alloys. • The activation energy of Al-3%Ga-5.25%In-1.75%Sn is 39.2 kJ/mol. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the results of a hybrid air independent propulsion based on fuel cells for small submarines. The weight and volume of the investigated propulsion, and the major tactical and technical characteristics of the 540-tonne submarine equipped with this propulsion have been determined. Five onboard systems for the hydrogen storage or generation, and the oxygen storage are considered. Combining a micro-balloon hydrogen system with the cryogenic oxygen storage is the best solution for the propulsion. The submerged endurance and range improved 32.1-64.8 times, as compared to just battery. The indiscretion ratio equals zero at cruising speeds of less than 7.1 knots, while at higher speeds, this value has dramatically decreased, and submarine secrecy has increased significantly. [ABSTRACT FROM AUTHOR]

Summary: It reports how to increase the overall catalytic performance of precious platinum nanocatalysts in hydrolytic dehydrogenation of ammonia borane which requires enhancement of both catalytic activity and reusability of the nanocatalysts as well as the fraction of active sites over the total platinum atoms. The following approaches are reported for increasing the utilization efficiency of platinum‐based nanocatalysts: (i) The use of colloidal nanoparticles is an efficient way of increasing catalytic activity. However, colloidal platinum(0) nanoparticles are unstable against agglomeration and therefore not reusable. (ii) Supporting the platinum(0) nanoparticles on large surface area materials can increase their stability. Carbonaceous support materials provide moderate activity for platinum(0) nanoparticles but not stability because of the weak metal‐support interaction. (iii) Selecting suitable oxide support can help in increasing the catalytic efficiency of platinum nanocatalysts. Particularly, using reducible oxides as support provides a favorable metal‐support interaction leading to a notable increase in the catalytic activity and stability of platinum(0) nanoparticles. (iv) The utilization efficiency of the precious platinum nanocatalysts can be significantly enhanced by downsizing the nanoparticles and lowering the relative amount of platinum down to single‐atom; that is, using the single‐atom platinum nanocatalyst which, however, is limited by the amount of platinum as it cannot be increased because of unavoidable agglomeration. (v) The reusability of platinum(0) nanoparticles can be increased by using magnetic powder materials as support. Thus, the magnetically separable Pt0/CoFe2O4 and Pt0/Co3O4 nanoparticles possess superior catalytic activity plus outstanding reusability and hence, provide significant enhancement in catalytic performance or utilization efficiency of platinum(0) nanocatalysts in the evolution of H2 from the hydrolysis of ammonia borane. Consequently, all these ultimately lower the cost of platinum nanocatalysts. [ABSTRACT FROM AUTHOR]

Green hydrogen is becoming an increasingly important energy supply source worldwide. The great potential for the use of hydrogen as a sustainable energy source makes it an attractive energy carrier. In this paper, we discuss the potential of producing green hydrogen in Jordan. Aqaba, located in the south of Jordan, was selected to study the potential for producing green hydrogen, due to its proximity to a water source (i.e., the Red Sea). Two models were created for two electrolyzer types using MATLAB. The investigated electrolyzers were alkaline water (ALK) and polymeric electrolyte membrane (PEM) electrolyzers. The first model was used to compare the required capacity of the PV solar system using ALK and PEM from 2022 to 2025, depending on the learning curves for the development of these technologies. In addition, this model was used to predict the total investment costs for the investigated electrolyzers. Then, a techno-economic model was constructed to predict the feasibility of using this technology, by comparing the use of a PV system and grid electricity as sources for the production of hydrogen. The net present value (NPV) and levelized cost of hydrogen (LCOH) were used as indicators for both models. The environmental effect, according to the reduction of CO2 emissions, was also taken into account. The annual production of hydrogen was 70.956 million kg. The rate of hydrogen production was 19.3 kg/s and 1783 kg/s for ALK and PEM electrolyzers, respectively. The LCOH was 4.42 USD/kg and 3.13 USD/kg when applying electricity from the grid and generated by the PV system, respectively. The payback period to cover the capital cost of the PV system was 11 years of the project life, with a NPV of USD 441.95 million. Moreover, CO2 emissions can be reduced by 3042 tons/year by using the PV as a generation source, instead of fossil fuels to generate electricity. The annual savings, with respect to the reduction of CO2 emissions, was USD 120,135. [ABSTRACT FROM AUTHOR]

• This work constitutes a timely and important advancement in the interdisciplinary area of photocatalytic water splitting and machine learning technology. • The machine learning screening method proposed in this paper can greatly accelerate the progress of photocatalyst discovery. We showed that ten potential photocatalysts can be selected from 860 metal oxides within seconds based on the established screening model. • A prediction model of energy level was established based on regression algorithm. By using regression algorithm, we can train the prediction model based on a relatively small dataset, and the accuracy of the prediction model is very high (R 2 = 0.908). • An effective photocatalyst of CsYO 2 was selected. We used DFT calculations to probe the free energy change during hydrogen emission reaction and oxygen emission reaction, and the effectiveness of CsYO 2 was verified. • Besides, the machine learning screening method proposed in the paper can be extended to screen multi-component metal oxide photocatalysts by establishing its corresponding material library. Photocatalytic water splitting represents a sustainable avenue for hydrogen production, yet the traditional trial-and-error approach for identifying efficient photocatalysts among numerous candidates is cumbersome. In this paper, we introduce a machine learning (ML)-driven approach for rapid screening of promising metal oxide photocatalysts for hydrogen generation. This methodology comprises three key steps: the construction of a comprehensive material library, ML-accelerated material screening, and Density Functional Theory (DFT) calculations for verification. Through this process, we successfully identify ten metal oxides with good energy levels and charge carrier transport properties from an initial library of 860 candidates. Notably, CsYO 2 emerges as a standout candidate, exhibiting excellent photocatalytic water-splitting performance on its (001) crystal face, with Y atoms identified as active sites through DFT calculations. This study demonstrates the efficacy of applying machine learning to the precise and rapid screening of vast material databases, paving the way for discovering novel and efficient photocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: Chemical looping hydrogen generation (CLHG) is a hydrogen production process with broad prospects for its advantages of not requiring H2 purification process and direct CO2 capture. Presently, the research on the integrated system of CLHG focuses on the impact of integrated processes and operating variables on the overall energy efficiency and exergy efficiency of the system. However, the research on the matching relationship between quantity and quality in the process of energy conversion is insufficient, and the flow direction of exergy and the specific exergy destruction process for equipment are not clear. The integrated system of coal gasification (CG) and three reactors CLHG was established in this paper with a hydrogen production efficiency of 42.55% and system exergy efficiency of 52.98%. This paper studied the exergy flow direction and efficiency of the equipment in the system, providing the improved direction for the amelioration of the system; a detailed description was present on the change process of energy quality in each equipment with energy quality factor, and the concept of energy quality factor ratio was proposed as an evaluation tool for matching the quantity and quality of energy in the system. It is calculated that the ratio of energy quality factor of the integrated system of CG and CLHG is 0.944. By comparing with the energy quality ratio of the traditional CG hydrogen production system (0.896), it can be concluded that the integrated system of CG and CLHG has a better energy matching relationship. [ABSTRACT FROM AUTHOR]

Natural cellulose substances have been proven to be ideal structural templates and scaffolds for the fabrication of artificial functional materials with designed structures, psychochemical properties and functionalities. They possess unique hierarchically porous network structures with flexible, biocompatible, and environmental characteristics, exhibiting great potentials in the preparation of energy‐related materials. This minireview summarizes natural cellulose‐based materials that are used in batteries, supercapacitors, photocatalytic hydrogen generation, photoelectrochemical cells, and solar cells. When natural cellulose substances are employed as the structural template or carbon sources of energy materials, the three‐dimensional porous interwoven structures are perfectly replicated, leading to the enhanced performances of the resultant materials. Benefiting from the mechanical strengths of natural cellulose substances, wearable, portable, free‐standing, and flexible materials for energy storage and conversion are easily obtained by using natural cellulose substances as the substrates. [ABSTRACT FROM AUTHOR]

Purpose: Alternating current (AC) corrosion is a type of corrosion that occurs in buried pipelines under AC stray current interference, which can increase the hydrogen embrittlement sensitivity of pipelines. However, rare research works have been conducted on the hydrogen permeability characteristics of pipeline steel under AC stray current interference. The purpose of this paper is to study hydrogen permeation behavior of X80 steel under AC stray current interference. Design/methodology/approach: In this paper, the hydrogen permeation behavior of X80 steel under AC interference is studied by AC hydrogen charging experiment in a dual electrolytic cell. The relationship between hydrogen evolution rate and hydrogen permeation flux is studied using the gas collection method. The difference between AC hydrogen permeability and direct current (DC) hydrogen permeability is also discussed. Findings: The anodic dissolution caused by AC corrosion promotes the chemical desorption reaction of the adsorbed hydrogen atoms on the surface, reducing the hydrogen atom absorption ratio by 70%. When the AC is smaller than 150░ A/m2, the hydrogen permeation process is controlled by the hydrogen atom generation rate, and the hydrogen permeation flux increases with the increase in hydrogen atom generation rate. When the AC exceeds 400░ A/m2, the hydrogen permeation process is controlled by the absorption ratio. The hydrogen permeation flux decreases with the decrease in the absorption ratio. Under AC interference, there is a maximum hydrogen permeation flux that linearly correlates to the H+ concentration in the solutions. Originality/value: The high-strength steel is very sensitive to hydrogen embrittlement, and X80 steel has been widely used in oil and gas pipelines. To date, no research has been conducted on the hydrogen permeation behavior of pipeline steel under AC interference, and the hydrogen permeability characteristics of pipeline steel under AC interference are not clear. The research results of this paper are of great significance for ensuring the intrinsic safety of high-strength pipelines under AC stray current interference. [ABSTRACT FROM AUTHOR]

The ionic liquid (IL) 1‐octyl‐3‐methylimidazolium bromide/FeCl3 [OMIM]Br/FeCl3 was prepared with three molar ratios of [OMIM]Br/FeCl3 (0.5 : 1, 1 : 1, and 2 : 1), and fully characterized through 1H and 13C NMR, Fourier‐transform IR, and Raman spectroscopic techniques. The optical properties of the prepared [OMIM]Br/FeCl3 ILs were revealed via diffuse reflectance and photoluminescence spectra. The photocatalytic activity of [OMIM]Br/FeCl3 ILs as homogenous photocatalysts were investigated towards hydrogen generation from methanol/water mixtures under visible light irradiation. The FeCl3‐based IL with [OMIM]Br/FeCl3 molar ratio of 1 : 1 exhibited the highest visible light photocatalytic activity with a hydrogen productivity of 243.2 mmol h−1 g−1 and a hydrogen purity of 95.5 %; such a high hydrogen yield and purity was reported for the first time. It was proposed that [OMIM] Br acted as an electron acceptor, which delayed the electron‐hole pair recombination of FeCl3. Also, [OMIM] Br could capture the produced carbon dioxide that is released with hydrogen gas. Additionally, [OMIM] Br/FeCl3 could be reused six times with nearly the same photocatalytic activity. These outstanding credits in terms of hydrogen generation rate and purity plus the economic feasibility, through several cycles of reuse, could certify such an IL as a promising photocatalyst for employment in water splitting. This paper suggests ways forward for research to develop the use of ILs as efficient and effective photocatalysts for hydrogen generation via water splitting. [ABSTRACT FROM AUTHOR]

CoH SB x sb PO SB y sb nanoparticles exhibit a better hydrogen evolution reaction improvement effect on the CdIn SB 2 sb S SB 4 sb photocatalyst than Pt nanoparticles. These eleven papers were devoted to achieving high-efficiency photocatalysts by broadening the light absorption range, inhibiting the photo-induced electrons and holes recombination, and promoting the extraction of photo-induced charges for chemical reactions. The CoH SB x sb PO SB y sb accelerates the hole transfer and inhibits the electron and hole recombination, thus promoting the photocatalytic hydrogen evolution reaction activity under visible light. [Extracted from the article]

In this paper, the properties and evolution during the calcination process of hydrolysis by−products from the reaction between Al−based composites and water for hydrogen generation were systematically investigated. The results showed that the main phases of by−products included AlOOH and InSn4. The amorphous product possessed a large Brunauer−Emmett−Teller (BET) surface area with 276.77 m2/g and high porosity properties with 0.37 cm3/g. The phase transformation of by−products from AlOOH to γ−Al2O3, δ−Al2O3, and α−Al2O3 occurred during the calcination process. It appears that the by−products can be used as raw materials for the preparation of Al2O3 with different crystal structures. Discussion on the properties and evolution of hydrolysis by−products are beneficial to product reuse and recovery. In this way, the cost reduction of hydrogen production via Al−water reaction can be realized, promoting the sustainable development of hydrogen production from Al−water reaction. [ABSTRACT FROM AUTHOR]

Considering the high calorific value and low-carbon characteristics of hydrogen energy, it will play an important role in replacing fossil energy sources. The production of hydrogen from renewable energy sources for electricity generation and electrolysis of water is an important process to obtain green hydrogen compared with classic low-carbon hydrogen production methods. However, the challenges in this process include the high cost of liquefied hydrogen and the difficulty of storing hydrogen on a large scale. In this paper, we propose a new route for hydrogen storage in metals, namely, electricity generation from renewable energy sources, electrolysis to obtain metals, and subsequent hydrogen production from metals and water. Metal monomers facilitate large-scale and long-term storage and transportation, and metals can be used as large-scale hydrogen storage carriers in the future. In this technical route, the reaction between metal and water for hydrogen production is an important link. In this paper, we systematically summarize the research progress, development trend, and challenges in the field of metal to hydrogen production. This study aim to aid in the development of this field. • A new route for hydrogen storage and production via metals on a large scale is proposed. • Electrolysis to obtain metals by green electricity, and subsequent hydrogen production from metals and water. • Metal monomers facilitate large-scale and long-term storage and transportation. • Metals can be used as large-scale hydrogen storage carriers in the future. • Metal-water hydrogen production can make full use of renewable energy without carbon dioxide. [ABSTRACT FROM AUTHOR]

Due to there is no better way to exploit depleted gas reservoirs, and hydrogen can generate from natural gas combustion. In this paper, the possibility of in-situ hydrogen generation in air injected gas reservoirs was determined through pseudo dynamic experiments. The study indicated that higher temperature and steam/methane ratio can generate more hydrogen, and the temperature should not be lower than 600 °C within gas reservoirs. The debris has positive catalysis for hydrogen generation. The maximum mole fraction of hydrogen was 26.63% at 600 °C. [ABSTRACT FROM AUTHOR]

A potential method of storing and transporting hydrogen safely in a cost-effective and practical way involves the utilization of molecules that contain hydrogen in their structure such as ammonia. Because of its high hydrogen content and carbon-free molecular structure, as well as the maturity of related technology (easy liquefaction), ammonia has gained attention as a "hydrogen carrier" for the generation of energy. Unfortunately, hydrogen production from ammonia requires an efficient catalyst to achieve high conversion at low reaction temperatures. Recently, very attractive results have been obtained with low-surface-area materials. This review paper is focused on summarizing and comparing recent advances in novel, economic and active catalysts for this reaction, paying particular attention to materials with low surface area such as silicon carbide (SiC) and perovskites (ABO3 structure). The effects of the supports, the active phase and the addition of promoters in such low-porosity materials have been analyzed in detail. Advances in adequate catalytic systems (including support and active metal) benefit the perspective of ammonia as a hydrogen carrier for the decarbonization of the energy sector and accelerate the "hydrogen economy". [ABSTRACT FROM AUTHOR]

This paper reviews the progress in applying the plasma-driven solution electrolysis (PDSE), which is also referred to as the contact glow-discharge electrolysis (CGDE) or plasma electrolysis, for hydrogen production. The physicochemical processes responsible for the formation of PDSE and effects occurring at the discharge electrode in the cathodic and anodic regimes of the PDSE operation are described. The influence of the PDSE process parameters, especially the discharge polarity, magnitude of the applied voltage, type and concentration of the typical electrolytic solutions (K2CO3, Na2CO3, KOH, NaOH, H2SO4), presence of organic additives (CH3OH, C2H5OH, CH3COOH), temperature of the electrolytic solution, the active length and immersion depth of the discharge electrode into the electrolytic solution, on the energy efficiency (%), energy yield (g(H2)/kWh), and hydrogen production rate (g(H2)/h) is presented and discussed. This analysis showed that in the cathodic regime of PDSE, the hydrogen production rate is 33.3 times higher than that in the anodic regime of PDSE, whereas the Faradaic and energy efficiencies are 11 and 12.5 times greater, respectively, than that in the anodic one. It also revealed the energy yield of hydrogen production in the cathodic regime of PDSE in the methanol–water mixture, as the electrolytic solution is 3.9 times greater compared to that of the alkaline electrolysis, 4.1 times greater compared to the polymer electrolyte membrane electrolysis, 2.8 times greater compared to the solid oxide electrolysis, 1.75 times greater than that obtained in the microwave (2.45 GHz) plasma, and 5.8% greater compared to natural gas steam reforming. [ABSTRACT FROM AUTHOR]

The article is devoted to the problem of proton-exchange membrane fuel cells (PEMFCs) integration into power supply systems. A hybrid energy complex (HEC) based on PEMFCs and lithium iron phosphate batteries can be used as a reliable energy source. It is necessary to properly determine the PEMFC characteristics in order to develop a PEMFC-based HEC prototype and its control algorithms. This paper presents a 1 kW PEMFC's test results in steady and dynamic modes. The dependences of the average hydrogen consumption per 1 min, the volume of hydrogen for the generation of 1 kWh, the PEMFC efficiency on the load current were obtained and an analysis of these dependences for steady operation modes was performed. A range of load changes beyond which the efficiency of the PEMFC significantly decreased and it was recommended to switch to the joint operation of the PEMFCs and batteries (or only batteries) was established. Diagrams of the PEMFC output voltage during the dynamic changes in loads are presented and an analysis of transient response characteristics was carried out. The air supply fans were found to affect the performance of PEMFCs. [ABSTRACT FROM AUTHOR]

This paper investigates the economics of a fuel cell bus fleet powered by hydrogen produced from electricity generated by a wind park in Austria. The main research question is to simultaneously identify the most economical hydrogen generation business model for the electric utility owning wind power plants and to evaluate the economics of operating a fuel cell bus fleet, with the core objective to minimize the total costs of the overall fuel supply (hydrogen production) and use (bus and operation) system. For that, three possible operation modes of the electrolyzer have been identified and the resulting hydrogen production costs calculated. Furthermore, an in-depth economic analysis of the fuel cell buses as well as the electrolyzer technology has been conducted. Results show that investment costs are the largest cost factor for both technologies. Thus, continuous hydrogen production with the smallest possible electrolyzer is the economically most favorable option. In such an operation mode (power grid), the costs of production per kg/H 2 were the lowest. However, this means that the electrolyzer cannot be solely operated with electricity from the wind park, but is also dependent on the electricity mix from the grid. For fuel cell buses, the future cost development will depend very much on the respective policies and funding programs for the market uptake, as to date, the total cost of use for the fuel cell bus is more than two times higher than the diesel bus. The major final conclusion of this paper is that to make fuel cell electric busses competitive in the next years today severe policy interferences, such as subsidies for these busses as well as electrolyzers and bans for fossil energy, along with investments in the setup of a hydrogen infrastructure, are necessary. Cost analysis of a fuel cell electric bus and three hydrogen production operation models. [Display omitted] • Economic analysis of fuel cell buses and green hydrogen production. • Identification of the most suitable electrolyzer operation model. • Investment costs are still the largest cost component. • Technological learning and policy funding schemes may decrease the costs. [ABSTRACT FROM AUTHOR]

In this paper, density functional theory (DFT) was used to study the reaction mechanism of the production of hydrogen peroxide from oxygen and water catalyzed by graphene supported metal (Al, Zn, and Fe) catalysts. By comparing the supported stability of metal at different sites on graphene surface, the optimal support sites are determined and then a stable catalyst model is selected. Two different reaction paths for the synthesis of hydrogen peroxide and a competitive reaction path for the generation of hydrogen are discussed, the microscopic reaction mechanism of the synthesis of hydrogen peroxide catalyzed by water and oxygen is investigated in detail. The stable structures of reactants, intermediates, and products in each path are optimized. By comparing the activation energies of different reaction paths, the optimal reaction paths are obtained, and the possibility of side reaction products is predicted. At the same time, the electron density, band structure, and density of states characteristics of these graphene supported metal catalysts are studied. The correlation between the physical properties of the three catalysts and their catalytic performances is analyzed. It is predicted that Al, Zn, and Fe catalysts supported by graphene may have the ability to directly generate hydrogen peroxide in industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

The paper reports a strategy to synthesize Cd0.9Co0.1S nanorods (NRs) via a one-pot solvothermal method. Remarkably, the pencil-shaped Cd0.9Co0.1S NRs with a large aspect ratio and good polycrystalline plane structure significantly shorten the photogenerated carrier transfer path and achieve fast separation. An appropriate amount of Co addition enhances visible light-harvesting and generates a photothermal effect to improve the surface reaction kinetics and increases the charge transfer rate. Moreover, the internal electric field facilitates the separation and transfer of carriers and effectively impedes their recombination. As a result, the optimized Cd0.9Co0.1S NRs yield a remarkable H2 evolution rate of 8.009 mmol·g−1·h−1, which is approximately 7.2 times higher than that of pristine CdS. This work improves the photocatalytic hydrogen production rate by tuning and optimizing electronic structures through element addition and using the photothermal synergistic effect. [ABSTRACT FROM AUTHOR]

The photocatalytic hydrogen production efficiency of a single SrTiO3 photocatalytic catalyst is often low, which is mainly due to the serious combination of electrons and holes produced by photocatalysis as well as the mismatch of the redox capacity and light absorption range. Construction of semiconductor heterojunctions can solve these problems. CdS has a narrow band gap, which can effectively utilize visible light, and it has a band structure matched with that of SrTiO3. Therefore, CdS is considered as an ideal candidate for constructing heterojunctions with SrTiO3. In this paper, bamboo pulp fibers were used as the substrate, and SrTiO3 was coated on the substrate through the solvothermal process. CF/SrTiO3 rich in oxygen vacancies was formed by high temperature carbonization, and heterojunctions were formed by loading CdS on the surface of the CF/SrTiO3 composite material through the hydrothermal method, thus obtaining one-dimensional CF/SrTiO3/CdS core–shell photocatalysts. The structure and photocatalytic hydrogen production performance of the CF/SrTiO3/CdS core–shell photocatalysts were mainly studied. The photocatalytic hydrogen production experiment showed that the hydrogen production rate of the CF/SrTiO3/CdS-2 sample under the optimized process was as high as 577.39 μmol/g·h, which was about 11 times that of the CF/SrTiO3 sample. In this composite photocatalytic material system, the loading of the CdS nanospheres could enhance the visible light absorption capacity of the composite catalyst, promote the rapid separation and high-speed migration of photocarriers, and significantly improve the photocatalytic activity. [ABSTRACT FROM AUTHOR]