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With advantages such as low cost, high stability, and ease of production, visible light photocatalytic C3N4 with a unique microscopic layered structure holds significant potential for development. However, its hydrogen production efficiency remains low due to the pronounced recombination of photo-generated charge carriers and limited surface reaction sites. Normally, the photocatalytic performance of C3N4 can be enhanced by loading noble metals with surface plasmon resonance. It is worth noting that the size of noble metal nanoparticles has a great influence on photocatalytic performance. In this study, accurate controlling of the size and distribution of Au nanoparticles was achieved on the surface of C3N4 by introducing amino groups to improve photocatalytic performance. Results show that uniformly distributed Au nanoparticles in the range of 2–6 nm can be obtained on C3N4 with a remarkable enhancement of hydrogen production efficiency, which is about 114 times the property of pure C3N4. The small-sized and uniformly distributed Au nanoparticles can provide more reaction sites and increase the separation of photo-generated charge carriers, in turn improving Au/NH3–C3N4 photocatalytic hydrogen release rate to 6.85 mmol g−1 h−1. This work offers a facile way to enhance photocatalytic performance by controlling the size of metal nanoparticles on C3N4 precisely. [ABSTRACT FROM AUTHOR]

This study investigates the impact of biaxial strain on monolayer black phosphorus (BP) through first-principles calculations, confirming its stability and subsequently modifying its photocatalytic performance. Under biaxial strain, BP exhibits a direct bandgap suitable for photocatalytic hydrogen production during water splitting, albeit with limitations due to its valence band maximum edge. A distinctive GaN/BP heterojunction is proposed, featuring a direct bandgap and advantageous band edge positions conducive to efficient photocatalytic overall water splitting. Under the influence of biaxial strain, the heterojunction type undergoes a transition from direct type-I to direct type-II and Z, augmenting the separation of photoexcited electrons and holes and markedly enhancing the efficiency of photocatalytic hydrogen production. Furthermore, the heterojunction exhibits commendable capabilities in absorbing visible light. This research provides a promising avenue to surmount the constraints associated with monolayer BP in photocatalysis, offering valuable insights for the development of efficient photocatalytic materials. [ABSTRACT FROM AUTHOR]

Substituting slow oxygen evolution reaction (OER) with thermodynamically favorable urea oxidation reaction (UOR) is considered as one of the feasible strategies for achieving energy-saving hydrogen production. Herein, a uniform layer of NiMoO4 nanorods was grown on nickel foam by a hydrothermal method. Then, a series of Ni-MoOx/NF-X nanorod catalysts comprising Ni/NiO and MoOx (MoO2/MoO3) were prepared through regulating annealing atmosphere and reduction temperature. The optimized Ni-MoOx/NF-3 with a large accessible specific area can act as a bifunctional catalyst for electrocatalytic anodic UOR and cathodic hydrogen evolution reaction (HER). At a current density of 100 mA cm−2, the introduction of urea can significantly reduce the overpotential of Ni-MoOx/NF-3 by 210 mV compared to OER. In addition, Ni-MoOx/NF-3 has a higher intrinsic activity than other catalysts. It only requires −0.21 and 1.38 V to reach 100 mA cm−2 in HER and UOR, respectively. Such an excellent performance can be attributed to the synergistic function between Ni and MoOx. The presence of metallic Ni and reduced MoOx in pairs is beneficial for improving the electrical conductivity and modulating the electronic structure, resulting in enhancing the electrocatalytic performance. When assembling Ni-MoOx/NF-3 into an overall urea–water splitting system, it can achieve energy-saving hydrogen production and effective removal of urea-rich wastewater. [ABSTRACT FROM AUTHOR]

Plasmonic catalysis triggers the dissociation of H 2 or adsorbed O 2 (sluggish processes) under continuous wave excitation via plasmon decay. This is coupled to interband or intraband excitation of d-band or sp-band, respectively, to levels above fermi level of metals. Here, we have studied the plasmonic and photocatalytic behavior in an environment friendly medium with AM 1.5 G sunlight of CuO/ Cu 2 O thin films fabricated by pulsed laser deposition technique in vacuum with varying thickness. We have achieved ∼ 0.59 kmol h − 1 g − 1 H 2 production in the CuO/ Cu 2 O film with a thickness of ∼ 27 nm. The role of plasmons with metal–dielectric and semiconductor–semiconductor interfaces is conducted through both experimental and theoretical approaches. The results suggest that the impact of plasmonic catalysis/synthesis is subject to the dimension, composition, and band alignment of two interface materials. [ABSTRACT FROM AUTHOR]

There is growing interest in the use of hydrogen as a transportation fuel but the environmental benefits of using hydrogen depend critically on how it is produced and distributed. Leading alternatives to using fossil natural gas to make hydrogen through the conventional method of steam methane reforming include using electrolyzers to split water into hydrogen and oxygen, and the use of biogas as an alternative feedstock to fossil natural gas. This report examines the latest carbon intensity (CI) estimates for these and various other hydrogen production processes, adding important nuances to the general “colors of hydrogen” scheme that has been used in recent years. CI values for hydrogen production can vary widely both within and across hydrogen production pathways. The lowest CI pathways use biomass or biogas as a feedstock, and solar or wind power. The report also analyses jobs creation from new hydrogen production facilities and shows that these benefits can be significant for large-scale facilities based on either future biomass/biogas-to-hydrogen or solar-hydrogen production technologies. Recommendations include setting stricter goals for the state’s Low Carbon Fuel Standard (LCFS) program to continue to reduce the carbon footprint of California’s transportation fuels.

The potential of methanol reforming systems to greatly improve productivity in chemical reactors has been limited, due in part, to the effect of mass transfer limitations on the production of hydrogen. There is a need to determine whether or not a microchannel reforming reactor system is operated in a mass transfer-controlled regime, and provide the necessary criteria so that mass transfer limitations can be effectively eliminated in the reactor. Three-dimensional numerical simulations were carried out using computational fluid dynamics to investigate the essential characteristics of mass transport processes in a microchannel reforming reactor and to develop criteria for determining mass transfer limitations. The reactor was designed for thermochemically producing hydrogen from methanol by steam reforming. The mass transfer effects involved in the reforming process were evaluated, and the role of various design parameters was determined for the thermally integrated reactor. In order to simplify the mathematics of mass transport phenomena, use was made of dimensionless numbers or ratios of parameters that numerically describe the physical properties in the reactor without units. The results indicated that the performance of the reactor can be greatly improved by means of proper design of catalyst layer thickness and through adjusting feed composition to minimize or reduce mass transfer limitations in the reactor. There is not an effective method to reduce channel dimensions if the flow rate remains constant, or to reduce fluid velocities if the residence time is kept constant. The rate of the reforming reaction is limited by mass transfer near the entrance of the reactor and by kinetics further downstream, when the heat transfer in the autothermal system is efficient. Finally, the criteria that can be used to distinguish between different mass transport and kinetics regimes in the reactor with a first-order reforming reaction were presented.

Computational fluid dynamics uses numerical methods and algorithms to solve and analyse problems that involve fluid flows. Computers may be used to perform the calculations required to simulate the interaction of liquids and gasses with a surface defined by boundary conditions. Thermodynamics is the science of the relationship between heat, work, temperature, and energy. Computational modelling for microchannel reactor design was performed to investigate the effects of various factors on the efficiency and performance of an autothermal reforming system. The yield and productivity from the chemical process were determined by performing computational fluid dynamics and thermodynamic analysis. Strength and weakness were assessed under different reaction conditions. Design recommendations were provided and operation strategies were mapped out. The results indicated that operation at millisecond contact times is feasible, but optimisation of reaction conditions is necessary to balance efficiency and performance. The conversion to hydrogen is influenced greatly by the feed composition, which must be controlled precisely within certain needed limits to maximize the yield and productivity from the autothermal reforming process while avoiding the problems of combustion or explosion. Additionally, the efficiency difference between feed compositions is determined by thermodynamic analysis. The calculated output power of the autothermal reforming reactor is of the order of thousands of kilowatts per cubic meter.

High-efficiency and low-cost electrocatalysts play an important role in clean hydrogen production through electrocatalytic water decomposition. Therefore, it is of great significance to develop an effective method to retrieve rusty stainless steel and facilitate the slow oxygen evolution reaction (OER) for an environment-friendly and sustainable society. Herein, we developed a method to synthesize Fe–Ni bimetallic hydroxide (RSS-LDH) using chloride ions to corrode rusty stainless steel, which can be used as an efficient and cheap catalyst for OER and hydrogen evolution reaction (HER). We found that RSS-LDH has good electrocatalytic performance toward OER (η100 = 340 mV) and HER (η100 = 310 mV). In addition, RSS-LDH can be used as an active bifunctional catalyst in overall water splitting with a low cell voltage of 1.42 V at 10 mA cm−2 (1.64 V at 100 mA cm−2) and stable operation of 10 h (100 mA cm−2). This strategy can provide a new method for the recovery of rusty stainless steel and provide a new application for electrocatalysis and energy transformation. [ABSTRACT FROM AUTHOR]

Transition metal sulfides are promising non-noble metal catalysts for hydrogen production through electrochemical water splitting due to their rich redox behaviors, good conductivity and stability. Herein, mesoporous Cu2MoS4 nanocubes were rapidly synthesized at room temperature via a novel electron beam irradiation-assisted method. During the electron beam irradiation process, a large number of free radicals were produced. These radicals are highly active and effectively accelerate the rapid formation of Cu2MoS4 nanocubes with I-phase. The as-obtained Cu2MoS4 nanocubes presented a mesoporous structure, which not only provides abundant electrocatalytic active sites but also facilitates the diffusion of electrolyte and the overflow of H2 bubbles. As a result, the titled catalyst exhibits good electrocatalytic activity toward the hydrogen evolution reaction (HER) in acidic, neutral and alkaline electrolytes. Specifically, the catalyst with an irradiation dose of 300 kGy exhibited the best HER performance with low overpotentials of 160.2 mV, 256.2 mV and 225 mV to achieve a current density of 10 mA cm−2 in 0.5 M H2SO4, 1 M PBS and 1 M KOH, respectively. This work demonstrates the effectiveness of electron beam-assisted synthesis in producing well-defined nanostructured catalysts for water splitting. [ABSTRACT FROM AUTHOR]

By-products of the hydrolysis reaction in the copper-chlorine thermochemical cycle for hydrogen production are key to the final thermal and hydrogen efficiency. The current study focuses on the influences of reaction time, temperature, and steam partial pressure on the hydrolysis reaction and by-product formation mechanism via experimental and multiple analytical methods. The result demonstrates that the hydrolysis reaction of CuCl 2 and steam converts to CuCl and Cu 2 OCl 2 , with a high conversion of 97%, while the Cu 2 OCl 2 and CuCl 2 -CuO product mixtures exhibit interconversion capabilities. The increase of temperature increases the CuCl product content, while the decrease of steam partial pressure increases the by-product CuCl 2. Particle morphology and reaction thermodynamics are analyzed for main and by-products formation. Finally, the homogeneous reaction model and shrinking core model are used and compared for the activation energy of the formation of Cu 2 OCl 2 for the hydrolysis reaction and the effect of by-products. • Hydrolysis of Cu-Cl thermochemical cycle for H 2 production was investigated. • Formation and evolution of by-products were comprehensively analyzed with factors. • Morphology, pore size, and reaction thermodynamics were compared for by-product. • Hydrolysis reaction kinetics and product evolution mechanism were revealed. [ABSTRACT FROM AUTHOR]

Water electrolysis is one of the recent alternatives for the generation of clean fuels (Hydrogen) with no unwanted by-products. As primary energy sources, hydrocarbon-based fuels harm the environment due to greenhouse gas emissions. Researchers all over the globe have been working hard to make it economically viable. Despite the development of several water-splitting electrocatalysts, effective material catalysts with enhanced activity, specificity, and durability are still missing. Noble metals may be replaced with transition metal-based catalysts. Among them, copper sulfide is one of the significant electrocatalysts for water splitting. Because of its unique structural and electrochemical features, copper sulfide compounds reduced toxicity and developing material has a lot of potential in electrochemistry. The interpretations of CuS heterojunctions will also facilitate the productive and safe preparation of high-quality electrode materials for high-energy storage devices. In this article, we have discussed the significance of Copper sulfide-based heterojunctions as efficient electrocatalysts, including HER, OER, CO 2 reduction and ORR. Copper sulfide-based heterojunctions for supercapacitors (SCs) and Lithium-ion batteries (LIBs) are also comprehensively discussed. This paper discusses the structural and electrochemical properties of CuS, its nanocomposites, and the methods used for their production. This discussion examines the relationship between these characteristics and the criteria for electrocatalysts in the process of total water splitting and its related reactions. Consequently, this paper lays forth a plan for future research into green energy generation and storage using electrochemical materials that are efficient, safe for the environment, and financially feasible. • Focus on recent progress in copper sulfide-based nanocomposites for water splitting. • Advantages of CuS nanocomposites/nanostructures for water splitting are highlighted. • Mechanisms of OER, HER and Water splitting are systematically illustrated. • Applications of copper sulfide nanomaterials for ORR and CO 2 reduction are also discussed. • Applications of copper sulfide nanomaterials for energy storage are also highlighted. • Suggestions on further development of electrochemical and energy storage materials. [ABSTRACT FROM AUTHOR]

In order to recover the waste heat of high temperature metallic granules to produce steam for hydrogen production, a waste heat recovery cooling cylinder with cooling water channel is innovatively developed. The simulation is carried out based on DEM and soft sphere model to study the flow characteristics of ternary size metallic granules. The model of cooling cylinder is established and verified by comparing to the experiment data. The change rule of bed shape in the waste heat recovery cooling cylinder is examined, and the inclination angle, rotational speed and filling rate are assessed to find their influence on the flow characteristics of ternary size metallic granules. The results indicated that, with the increase of inclination angle, the axial velocity increases by 482.76%, which means the reduce of residence time of granules. With the increase of rotational speed, the axial velocity has an increase of 161.54%, the sum velocity increases by 158.49%, leading to a decrease of residence time. As the filling rate increases from 1.5% to 15.5%, the contact number has an increase of 91.53%, which lead to the increase of heat transfer area. The residence time and heat transfer area will directly affect the waste heat recovery efficiency, so a proper arrangement of granule flow is significant for enhancing the heat transfer efficiency. • The combination of waste heat recovery and hydrogen production was put forward. • A new cooling cylinder with cooling water channel was put forward. • The change rule of bed shape in the waste heat recovery cooling cylinder was examined. • The flow characteristics of ternary size metallic granules was revealed. [ABSTRACT FROM AUTHOR]

The Z-scheme CuBi 2 O 4 /Bi 2 O 3 photocatalyst films were prepared on copper foil, titanium foil and 430-stainless steel foil, respectively, by using incomplete solid-state reaction method. The photocatalytic organic pollutants degradation and simultaneous hydrogen production were achieved on both sides of the metal foils, respectively. The microstructure, composition and performance of photocatalyst films were studied through XRD, SEM, TEM, XPS, EDX, TPR, PL and EIS. In photocatalytic MB degradation and hydrogen evolution experiments, the influences of the Bi(OH) 3 precipitation spin-coating number, calcination temperature and calcination time on the photocatalytic activity of Z-scheme CuBi 2 O 4 /Bi 2 O 3 photocatalyst films were investigated. The effects of the three different metal foils were comprehensively compared when the experimental conditions of 2 coating layer Bi(OH) 3 precipitation, 500 °C calcination temperature, 2.0 h calcination time and 10 mg/L and 50 mg/L MB concentrations were adopted. Experimental results show that Cu|CuBi 2 O 4 /Bi 2 O 3 photocatalyst film has the best photocatalytic performance in three photocatalyst films. MB degradation ratio and H 2 evolution amount are 92.90% and 491.07 μmol/dm2, respectively, for Cu|CuBi 2 O 4 /Bi 2 O 3 photocatalyst film under visible light irradiation for 180 min, and that for Ti|CuBi 2 O 4 /Bi 2 O 3 photocatalyst film and SSF|CuBi 2 O 4 /Bi 2 O 3 photocatalyst film they are 89.70% and 415.18 μmol/dm2, 83.90% and 401.79 μmol/dm2, respectively. The MB degradation and H 2 evolution mechanisms of the Z-scheme CuBi 2 O 4 /Bi 2 O 3 photocatalytic system were proposed. In theory, this method may have broad application prospects in repairing organic wastewater and large-scale hydrogen evolution. • Several Z-scheme photocatalyst films loaded on different metal foils are prepared. • REDOX reactions can be conducted on both sides of prepared photocatalyst film. • Obtained photocatalyst film can realize the respective collection of H 2 and CO 2. • Acquired photocatalyst film has the good activity stability and reusability. [ABSTRACT FROM AUTHOR]

Biohydrogen represents a highly feasible and environmentally sustainable fuel alternative for the world's growing energy needs. However, technological advancements are still required for large-scale hydrogen utilization, particularly in determining the most advantageous technological path for recovering affordable and renewable hydrogen. Researchers have conducted numerous studies to determine the optimal technology for producing large-scale biohydrogen. However, no comprehensive systematic and bibliometric review presents an overview of the various production modes, i.e., the photo and dark fermentation techniques. This paper reviews recent research on biohydrogen production using dark and photofermentation modes, spanning over two decades, using Scopus data. The review highlights the growing push to integrate hydrogen production into larger bioenergy systems, focusing on improving the core processes and removing obstacles. Techniques like co-digestion and two-stage anaerobic digestion can increase production yields. The review also highlights the possibility of combining waste treatment with energy production to address environmental issues. Incorporating dark- and photo-fermentation processes in commercial hydrogen production shows greater potential for commercial use, potentially increasing yield. The study concluded by identifying challenges for the various modes of production and ways to overcome them. It also provided pertinent information on potential future research directions. • This study reviewed research work on dark and photo fermentation. • The bibliometric review approach was used to review over two decades of research. • The study identified challenges in both processes and proposed strategies to address them. • Co-digestion and two-stage anaerobic digestion can increase production yields. • China leads the publishing world with 3455 publications on the subject. [ABSTRACT FROM AUTHOR]

This study focuses on the potentiostatic electrodeposition of copper indium and cadmium sulfide (CuS, In 2 S 3 , and CdS) thin films on copper substrates, aiming to develop efficient electrocatalysts for the electrochemical reduction of CO 2 and sustainable hydrogen generation. Utilizing Cu Kα radiation for X-ray diffraction (XRD) analysis, the crystal structures of the electrodeposited films were confirmed, revealing well-defined crystalline phases. The films exhibited average particle sizes of 55.99 nm for CuS, 50.37 nm for In 2 S 3 , and 63.51 nm for CdS. Cyclic voltammetry and chronoamperometry were employed to optimize the deposition parameters, ensuring efficient nucleation and growth of the metal sulfide films. The electrochemical performance of the synthesized electrocatalysts was rigorously tested, demonstrating their potential for CO 2 reduction under optimized conditions with the highest efficiency for CdS electrodes. Additionally, the electrodeposited CuS and CdS are of the p-type, and In 2 S 3 is of the n-type semiconductor were studied and verified by the Mott–Schottky test. CuS, In 2 S 3 , and CdS were found to have donor and acceptor concentrations (N D) of 1.68 × 106, 1.44 × 105, and 8.9 × 105 cm3, respectively. The photoelectrochemical measurements of the electrodeposited metal sulfides were studied at ambient temperature and under illumination, providing higher photocurrent responses for CdS and demonstrating its strong potential as a photoelectrode material for CO 2 reduction. This work underscores the significance of facile electrochemical synthesis methods in developing cost-effective and scalable electrocatalysts, paving the way for their integration into photoelectrochemical systems for green energy applications. [Display omitted] • Potentiostatic electrodeposition was used for CuS, In 2 S 3 , and CdS thin films. • XRD confirms high crystal phase purity and well-defined crystallinity. • Average particle sizes: CuS 55.99 nm, In 2 S 3 50.37 nm, CdS 63.51 nm. • CdS demonstrates the highest efficiency in electrocatalytic performance. • The study supports scalable, eco-friendly methods for CO 2 and H 2 applications. [ABSTRACT FROM AUTHOR]

HI decomposition is the key step for hydrogen production in the thermochemical sulfur-iodine cycle. A HI decomposer with good performance usually has the characteristics of high HI decomposition rate, which is important for hydrogen production. Herein, a novel U-shaped decomposer was designed for HI decomposition. Thermodynamic calculations showed the negligible effect of pressure. The physical field modeling indicated that the U-shaped reactor exhibited the longer residence time and the lower pressure drop than the common straight reactor. The optimized experimental conditions for U-shaped reactor were experimentally and theoretically determined as the systematic weight hourly space velocity (WHSV) of 1000 h−1, HI mass flow of 1.42 g/min, and catalyst mass of 85 mg. Subsequently, a series of activated carbon (AC) supported monometallic and bimetallic catalysts showed superior catalytic performance toward HI decomposition in our optimized U-shaped reactor than that in straight reactor. Especially the 1% Pt/AC and 0.5% Pt-0.5% Ir/AC exhibited excellent HI decomposition rate of 20.79% and 21.26%, respectively. Both of them performed excellent stability, which are promising candidates for HI decomposition in U-shaped decomposer. These findings provide new ideas and methods for improving the performance of the HI decomposition and thereby the development of sulfur-iodine cycle for hydrogen production. [Display omitted] • A novel U-shaped HI decomposition reaction system was developed. • The key factors influencing HI decomposition was experimentally emphasized and theoretically modelled. • HI decomposition using monometallic and bimetallic catalysts in U-shaped reactor exhibited superior performance. • The 0.5% Pt-0.5% Ir showed the high HI decomposition rate of 21.26% and excellent stability. [ABSTRACT FROM AUTHOR]

The development of a catalyst exhibiting outstanding catalytic activity and robust stability for both the oxygen evolution reaction and hydrogen evolution reaction in alkaline media represents a substantial challenge. In this work, a NF/Ni@NiCoSP heterostructure bifunctional catalyst was developed via a sequent process of electrodeposition-hydrothermal-low temperature thermal pyrolysis sulphuration/phosphorization. The physical characterizations reveal that the as-prepared sample of NF/Ni@NiCoSP exhibits a porous nano-needles array structure and consists of both Ni 3 S 2 and Co 2 P phases with considerable boundaries. As a consequence, the NF/Ni@NiCoSP presents an ultralow overpotential of 47 mV and 260 mV at 10 mA cm−2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. When assembled to a two-electrode system, it only requires 1.53 V to reach 10 mA cm−2, which surpasses the commercial RuO 2 ‖Pt/C (1.61 V). The methanol oxidation reaction probing experiment suggests the easy desorption of ∗OH from active sites due to the decreased binding strength between ∗OH and the catalyst, thus optimizing the kinetics condition. Moreover, the in-situ Raman spectra reveal that NiOOH and CoOOH serve as active sites for OER while the metal sites for HER. Therefore, this work introduces a feasible strategy to design cost-effective and robust catalysts with excellent catalytic properties, thereby paving the way for water splitting. • MOR probing experiment suggesting the easy desorption of ∗OH from active sites. • The NiOOH and CoOOH serve as active site for OER while the metal sites for HER. • NF/Ni@NiCoSP heterostructure bifunctional catalyst was developed. [ABSTRACT FROM AUTHOR]

The production of hydrogen via green method is the need of the present time to overcome the world's energy demand. Several electrocatalysts were employed to study critical oxygen evolution process (OER), and, Hydrogen evolution process (HER), which are designed for water splitting to generate clean hydrogen fuel. Here, we used a low-cost approach to fabricate NiS/MoTe 2 , which resulted in increased catalytic activity for water splitting. The nanocomposite's unique structure provides a larger surface area of 94 m2 g−1, evaluated from BET technique, resulting in more active sites with enough charge transfer capacity and material stability over time. The composite material has a synergistic impact with improved active sites, resulting in a much-reduced overpotential of 274, and, 180 mV for OER, and, HER at 10 mA cm−2 current density, respectively. It also has a lower Tafel value of 48, and, 47 mV dec−1, indicating efficient charge transfer during OER process and high electrocatalytic activity on Nickel Foam electrode. Water electrolysis's enhanced efficiency is due to huge surface area, higher mass activity for 4 and 3.84 A g−1 for OER and HER, respectively. NiS/MoTe 2 has lower Rct of 219 mΩ and 36.2 Ω, and it shows conductivity of 0.0084, and, 0.0082 S m−1 for OER, and HER, respectively. The synthesized material has enhanced ionic conductivity of 0.0084 and 0.0082 S m−1 for OER, and HER, accordingly. This advancement has potential to simplify electron transfer and usher in a new age by providing an improved alternative for noble metal-based materials. [Display omitted] • A simple Hydrothermal approach for the synthesis of material was opted. • Electrocatalyst showcased smaller overpotentials of 274 and 180 mV, for OER and HER, respectively. • A smaller Tafel slope values of 48 and 47 mV/dec for OER and HER was observed, respectively. • The catalyst remained stable up to 50 h for both OER and HER. [ABSTRACT FROM AUTHOR]

The increasing demand for clean and renewable energy underscores the importance of hydrogen energy, with electrocatalytic water splitting being an efficient method for green hydrogen production. Platinum, while an excellent catalyst for hydrogen evolution reactions (HER), is hindered by high cost and scarcity. This study explores non-precious alternatives, focusing on MoS 2 due to its "platinum-like behavior." The 1T-2H MoS 2 loaded on N-doped carbon (NC) catalysts (1T-2H MoS 2 @NC) were synthesized through a one-step pyrolysis of melamine and ammonium thiomolybdate. Comprehensive analysis revealed that the 2H phase formed at 700 °C, transitioning to a biphasic 1T-2H composition at higher temperatures. The catalyst synthesized at 800 °C with a 1:8 reactant ratio demonstrated exceptional HER performance, with an overpotential of 175 mV at 10 mA cm−2 and a Tafel slope of 92.37 mV dec−1. This study highlights the potential of 1T-2H MoS 2 @NC as a cost-effective and efficient catalyst for sustainable hydrogen production. [Display omitted] • The one-step pyrolysis method was used to synthesize 1T-2H MoS 2 @NC- n - T catalyst. • With a 175 mV overpotential at 10 mA cm−2 and a 92.37 mV dec−1 Tafel slope, the catalyst excels in acidic media. • In the catalyst, the 1T phase and the 2H phase MoS 2 coexist. • MoS 2 and NC are tightly bonded to improve the conductivity and stability of the catalyst. [ABSTRACT FROM AUTHOR]

Amidst the increasing deployment of renewable electricity, the demand for energy storage rises. To address medium to long-term storage needs, utilizing excess electricity for hydrogen production emerges as one of the most promising solutions. In the context of a modern energy grid characterized by intermittent power sources and challenges in constructing large power plants in densely populated areas, the concept of a Decentralised Energy Systems (DES) network appears practical. Consequently, there is an urgent need for research into efficient micro Gas Turbine (mGT) units fuelled by hydrogen. Most notably, it is important to assess the impact of several key combustor design parameters to minimise the NO x emissions. As a result, the study provides optimal values for both the momentum (3–4) and the primary equivalence ratio's (0.3–0.4) in order to optimise the hydrogen injection depth and minimise the high temperature zones near the combustor head wall, which will curtail NO x emissions. • Rising demand for energy storage with renewable electricity growth. • Low NO x hydrogen mGT in a Distributed Energy Systems (DES) framework. • Research on design and optimisation of micromix combustor. • Optimise design of nozzles to minimise hydrogen injection depth and wall temperature. • Optimal values of momentum (3–4) and equivalence ratio (0.4) decrease typical high NO x causes. [ABSTRACT FROM AUTHOR]

Single-atom catalysts exhibit immense potential across diverse reactions, yet their synthesis and stability in acidic environments pose significant challenges. Herein, we introduce a facile one-step hydrothermal approach to fabricate Ru single-atom alloy catalysts (Ru SAAC) through the reaction of Ru and Ti precursors, followed by annealing in an argon atmosphere. Analysis via extended X-ray absorption fine structure spectroscopy and aberration-corrected scanning transmission electron microscopy confirms the atomically dispersed Ru alloy catalyst anchored on a TiO 2 support. Remarkably, Ru SAAC demonstrates exceptional electrocatalytic performance in the iodide oxidation reaction (IOR), achieving a benchmark current density of 10 mA/cm2 at a mere voltage of 0.64 V in acidic conditions within a three-electrode electrolyzer setup. Surpassing nanoscale Ru/TiO 2 and RuO 2 /TiO 2 counterparts, Ru SAAC exhibits the highest voltage efficiency (84.4%), lowest Tafel slope (36 mV/dec), and lowest overpotential (100 mV) under identical experimental conditions. This method enables facile control over Ru morphology. It enhances the kinetics and thermodynamic favorability of Ru SAAC in acidic media, opening avenues for synthesizing diverse transition metal-based single-alloy catalysts for varied applications. [Display omitted] • A simple one-step hydrothermal method to fabricate Ru single-atom alloy catalysts. • Achieving a low potential of 0.64 V at 10 mA/cm2, outperforming other Ru/TiO₂ catalysts. • Energy-saving iodide oxidation reaction favorable for coupling hydrogen production. • It gives highest voltage efficiency (84.4%), lowest Tafel slope (36 mV/dec), lowest overpotential. • Method offers easy control over Ru morphology, enhancing kinetics and stability in acidic media. [ABSTRACT FROM AUTHOR]

Considering the advantages of circulating fluidized bed in industrial-scale processing production. A new biofilm reactor, anaerobic circulating fluidized bed reactor (ACFBr), was initially proposed, and the hydrogen production of the reactor were completed by dark fermentation from synthetic wastewater. In this study, Escherichia coli and Polyamide 6-carrier were used to evaluate the effects of reactor fluidization velocity and particle circulation rate (Gs) on hydrogen production. The experiments were conducted across a range of fluidization velocities:1.1U t ,1.2U t ,1.3U t and 1.4U t (U t :terminal velocity), combined with the Gs of 0.320, 0.415 and 0.510 kg/m2·s) in a crossover experimental design. The system operated with synthetic wastewater of 2 g-glucose/L and hydraulic retention time of 4 h. The results indicated that: When the fluidization velocity reached 1.2U t , the ACFBr showed better performance, and the hydrogen production effect improved with the increase of Gs. Peak hydrogen yield and hydrogen production rate of the system was obtained under operating conditions of 1.2U t and 0.510 kg/m2·s, reaching 0.447 mol-H 2 /mol-glucose and 26.23 ml-H 2 /L·h, respectively. Maximum COD removal efficiency attained 35.75% under operating conditions of 1.2U t and 0.415 kg/m2·s. The predominant metabolites included acetic acid (341.65–392.08 mg/L), propionic acid (60.41–74.28 mg/L), butyric acid (98.26–121.12 mg/L) and ethanol (83.73–101.25 mg/L). Obtained results proved the feasibility and stability of ACFBr for long-term production of biohydrogen and chemical substances via dark fermentation. • Circulating fluidized bed is first applied in dark fermentation to produce hydrogen. • Effects of fluidization velocity and particle circulation rate on system are studied. • Feasibility and stability of anaerobic circulating fluidized bed system are verified. • Anaerobic circulating fluidized bed has great potential for energy conversion. [ABSTRACT FROM AUTHOR]

Sorption-enhanced steam reforming (SESR) is a promising intensified strategy for producing highly pure hydrogen through in-situ CO 2 removal by a sorbent. This work experimentally explores the SESR of simulated bio-oil (mixture of acetic acid, acetone, ethanol, and phenol) over Ni/CaO-based bifunctional materials (BFMs) stabilized by industrial wastes (i.e., fly ash (FA) and UpGraded Slag Oxides (UGSO)) in a fixed bed reactor. The impact of CO 2 concentration and steam on the sorption efficiency of BFM-UGSO was investigated and the most likely carbonation route of BFM-UGSO in the presence of steam was proposed using N 2 physisorption isotherms (BET) and scanning electron microscopy (SEM). Moreover, a sorption kinetic model for BFM-UGSO was successfully developed. Whereas both developed materials (BFM-UGSO and BFM-FA) show exceptionally high H 2 purity (96.2 % and 98.4 %, respectively) at 550 °C, BFM-UGSO exhibited a much longer pre-breakthrough time (30 vs 21 min). Interestingly, BFM-UGSO showed remarkable cyclic stability with a CO 2 sorption capacity decay of less than 1 % along the 18 carbonation-regeneration cycles. It can be mainly attributed to the uniform distribution of mixed oxides generated by the interaction of Ni and CaO with metal oxides present in UGSO during material preparation. The inert phases, e.g., MgFe 2 O 4 , Fe 2 Al 2 O 4 , NiFe 2 O 4 , and Ca 2 Fe 2 O 5 (identified by X-ray diffraction patterns (XRD)) significantly hindered the sintering of CaO particles and limited pore structure failure. During the carbonation reaction, an increase in CO 2 concentration accelerated the kinetically controlled step of the carbonation reaction. Nevertheless, CaO conversion was found to be less affected for CO 2 concentrations exceeding 30 vol %. On the other hand, the morphological changes of the BFM-UGSO at wet conditions confirmed the ability of steam to promote solid-state diffusion in the product layer through the generation of abundant highly porous structure. The results of this work offer important insights into the SESR of bio-oil and open the door for further research in the exciting field of renewable hydrogen production. [Display omitted] • Intensified sorption-enhanced steam reforming of simulated bio-oil for renewable H 2 production. • UGSO-stabilized Ni/CaO bifunctional material (BFM-UGSO) offers remarkable efficiency. • The presence of steam highly improved the BFM-UGSO sorption capacity and cyclic stability. • A sorption kinetics model of UGSO-stabilized Ni/CaO bifunctional material was developed. [ABSTRACT FROM AUTHOR]

Green hydrogen will play an important role in reducing carbon emission in sectors like transportation, power supply, and industry. However, for it to become competitive technology, the costs related to hydrogen production must be reduced. Photocatalytic hydrogen production is one of the green hydrogen production methods that have the potential to become cost effective. So far, photocatalytic water splitting has mainly focused on hydrogen production from pure water systems, but it is practically attractive to study methods for seawater systems, which will make better use of available natural resources. In this study, we focus on the synthesis and characterization of a variety of metal dichalcogenide-embedded titanium dioxide (NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2) nanocomposite materials as photocatalysts for seawater splitting. The materials were synthesized using a facile hydrothermal method and were used for simulated seawater, seawater and deionized water splitting with 4 h of simulated solar illumination. The amounts of 48.11, 24.94, 15.04, and 2.78 mmolg−1 hydrogen were successfully produced with NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2, and pristine TiO 2 nanomaterials, respectively. Highest amount of H 2 with NiS 2 /TiO 2 photocatalyst can be attributed to the low bandgap of NiS 2, which acts as a co-catalyst. Our study clearly demonstrates that low-cost, noble-metal-free nanocomposite photocatalysts could be promising candidates for realizing efficient solar-to-hydrogen conversion from seawater splitting. • -NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 - nanocomposite materials were synthesized for photocatalytic water splitting in seawater, simulated seawater and deionized water using a facile hydrothermal method. • 48.11, 24.94, and 15.04 mmol/g of hydrogen were obtained with NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 nanomaterials in seawater. • Highest photocatalytic activity with metal chalcogenide-embedded titanium dioxide can be attributed to the low bandgap of metal chalcogenide material, which acts as a co-catalyst. • This study clearly demonstrates that low-cost, noble-metal-free nanocomposite photocatalysts could be promising candidates for realizing efficient solar-to-hydrogen conversion from seawater splitting. [ABSTRACT FROM AUTHOR]

Constructing heterojunctions of different dimensions formed by perovskite materials and semiconductor photocatalytic materials is an innovative idea for designing efficient photocatalysts. The combination of perovskite materials with photocatalytic materials for photocatalytic hydrogen evolution is less reported. In this paper, 3D LaCoO 3 /CdS heterojunction has been constructed by simple solvothermal method, and the interfacial charge transfer mechanism of S-scheme has been further demonstrated by DFT (density functional theory) calculations and ESR (electron spin resonance) experiments. The transfer mechanism effectively promotes the electron transfer and enhances the hydrogen evolution activity of the catalysts. The highest hydrogen evolution rate up to 18.91 mmol h−1 g−1, which is 9.60 times higher than pure CdS. In addition, it can be observed by SEM that the CdS nanoparticles are dispersed on the surface of the 3D network structure of LaCoO 3 , which effectively inhibits the agglomeration of CdS nanoparticles. Finally, TEM effectively demonstrated the effective interfacial contact between the different dimensions of LaCoO 3 and CdS. This contact facilitates the acceleration of charge transfer. This work provides a reference for the construction of perovskite-based S-scheme heterojunctions. 3D LaCoO 3 /CdS photocatalysts were prepared and a possible mechanism for the photocatalytic hydrogen production activity was proposed. [Display omitted] • Novel 3D LaCoO 3 /CdS S-scheme heterojunction successfully constructed. • LaCoO 3 as a low-cost and highly efficient photocatalyst for hydrogen precipitation. • LaCoO 3 /CdS-10 exhibited optimized H 2 production rate of 18.91 mmol h−1 g−1. [ABSTRACT FROM AUTHOR]

The aluminum-water reaction offers a promising method for clean hydrogen production, but it requires an effective catalyst. This study investigates the use of aluminum hydroxide (Al(OH) 3) as a catalyst for the aluminum-water reaction to generate hydrogen gas. Various aluminum hydroxide catalysts were synthesized and evaluated for their catalytic performance. The effects of catalyst source, synthesis conditions, quantity, and pH value of the reacting solution were systematically studied. The results demonstrate that self-synthesized, nano-sized Al(OH) 3 catalysts exhibit superior catalytic activity compared to commercial sources. Additionally, optimizing the pH value was found to significantly impact the hydrogen generation rate. Proper synthesized Al(OH) 3 is capable of completing hydrogen generation within 160 s at pH 11.6, while slightly higher pH value accelerates this reaction down to 60 s. Comparative studies with uncatalyzed reactions at higher pH levels (up to 14) showed significantly slower and incomplete hydrogen production. This research provides insights into developing efficient and sustainable catalytic systems for aluminum-water based hydrogen production. • Optimization of aluminum hydroxide for the hydrogen production from aluminum-water reaction. • Proper synthesized Al(OH) 3 is capable of completing hydrogen generation within 160 s at pH 11.6. • Uncatalyzed reactions at higher pH levels (up to 14) showed significantly slower and incomplete hydrogen production. • The knowledge can realize the production of green hydrogen from the reaction of aluminum scraps and water. [ABSTRACT FROM AUTHOR]

Here, a composite material comprised of inner ternary TiO 2 /CaTi 4 O 9 /CaTiO 3 nanoparticles and outer reduced graphene oxide (RGO) layer was fabricated and further applied as the photocatalyst for hydrogen production and Cr(VI) reduction. The PL result shows that the intimate interface between RGO and TiO 2 /CaTi 4 O 9 /CaTiO 3 composite can effectively promote the transfer of electrons (e - ), thus reducing its recombination on TiO 2 /CaTi 4 O 9 /CaTiO 3 , which provides much more electrons for H 2 production and the Cr (VI) reduction reactions. A remarkable improvement in H 2 production and Cr (VI) reduction were achieved over TiO 2 /CaTi 4 O 9 /CaTiO 3 modified with RGO. Notably, with optimum RGO content, the 1.0 wt%RGO-TiO 2 /CaTi 4 O 9 /CaTiO 3 showed the best H 2 production performance of 34.78 mmol h−1 g−1, which is 15.09 and 6.86 times higher than TiO 2 and CaTiO 3 , respectively. Moreover, an excellent Cr (VI) reduction rate of 53.79% was also achieved over 1.0 wt%RGO-TiO 2 /CaTi 4 O 9 /CaTiO 3 , which is 4.82 and 5.55 times higher than that of TiO 2 and CaTiO 3 , respectively. • Reduced graphene oxide (RGO) surface-modified TiO 2 /CaTi 4 O 9 /CaTiO 3 composite was synthesized. • The electron transfer to the reduced graphene oxide (RGO) and reduced charge recombination has been investigated. • RGO-TiO 2 /CaTi 4 O 9 /CaTiO 3 composite showed excellent photocatalytic performance in both H 2 production and Cr(VI) reduction. • A dual-Z-scheme was established in the ternary composite. [ABSTRACT FROM AUTHOR]

R2Mx is a new receiver-reactor concept for solar thermochemical water splitting cycles. The main difference to the current state-of-the-art is the use of a continuously operated reduction reactor with multiple mobile redox units. A plant model is developed for a version of the R2Mx concept with surrounding heliostat fields at MW scale. Performance estimates are derived over a large parameter space to characterize the plant and to identify possible technical challenges as well as research needs. Even without solid-solid heat recovery, the model predicts average annual plant efficiencies of up to 10.5% for multi MW receiver-reactors, which is comparable to commercial solutions. Furthermore, about 28% of the total energy input are energy losses occurring as highly concentrated radiation or as high temperature heat, emphasizing the improvement potential of the technology. Realizing the described enhancement options can turn this concept into an economic, large-scale fuel production technology. • The receiver-reactor R2Mx with surrounding heliostat fields is introduced and a comprehensive plant model is presented. • The performance of the complete solar thermochemical plant at MW scale was calculated for 432,000 parameter sets. • Different metrics are evaluated to characterize the plant and to identify technical challenges as well as research needs. • The resulting redox material heating profile in case of R2Mx shows substantial advantages compared to the state-of-the-art. • Competitive average annual plant efficiencies of up to 10.5 % and further significant improvement potential are identified. [ABSTRACT FROM AUTHOR]

g-C 3 N 4 is a promising metal-free photocatalyst for hydrogen production, whose application is difficult due to the low mobility of charge carriers and rapid electron-hole recombination. Here we propose a new route to improve its response to simulated sunlight and prevent electron-hole recombination by grafting mixed Ag–NiO (1:1 nominal Ag/NiO weight ratio) materials, as an alternative to platinum group metal co-catalysts. g-C 3 N 4 was prepared by urea pyrolysis, whereas Ag–NiO was prepared by a co-precipitation method, and then the composites were prepared by physical mixing using sonication-grinding. The presence of Ag–NiO on the surface plays a key role in accepting excited electrons and enhancing their lifetime for a subsequent reduction of protons to hydrogen. Hydrogen production was carried out from the photoreforming of ethanol under simulated sunlight. The results revealed that 2% (Ag–NiO)/g-C 3 N 4 is effective among others with 5.2 times higher H 2 production than unmodified g-C 3 N 4. The percentage of ethanol in the ethanol/water ratio is very important as we have found that with increasing its quantity, the evolution of hydrogen becomes significant. • New series of g-C 3 N 4 photocatalysts modified with mixed Ag–NiO. • Innovative synthesis of isolated Ag–NiO and (Ag–NiO)/g-C 3 N 4 composite. • Ag–NiO significantly reduces electron-hole recombination. • The optimal composite is 2% (Ag–NiO)/g-C 3 N 4. • Hydrogen evolution via ethanol photoreforming under simulated sunlight. [ABSTRACT FROM AUTHOR]

In the context of the growing use of hydrogen for decarbonization in combustion, understanding NO x emissions from hydrogen burners is crucial. This study focuses on the impact of partial premixing on NO x production in hydrogen flames using a coaxial injector with swirl. The goal is to expand conventional jet scaling laws to encompass additional physical phenomena. The flexible injection system employed allows the stabilization of various flame types depending on the operating conditions, and double-front flames are obtained in several configurations. Observing the limitations of known scaling laws, particularly in coaxial flows with low-velocity differences or swirl, we conduct experiments measuring NO x and flame volume. Two Large Eddy Simulations explore distinct flame configurations to deepen our understanding about coaxial jet and recirculating flames, especially in the presence of a secondary premixed front due to rich premixing. Our investigation delves into the relationship between NO production and strain rate, considering turbulent and strain-related timescales. Notably, the presence of a premixed flame front alters the velocity profile on the shear layer, and the observed relationship between strain and turbulence in jet flames does not hold for recirculating flames. Thanks to this new insight, we propose a novel formulation for NO x scaling in coaxial jets, leveraging existing literature on coaxial jet modeling. Additionally, we propose a simple model to represent the piloting strain rate for NO emission in recirculating flames. Intricate effects of both swirl and partial-premixing are then included in the derived NO x scaling laws. [Display omitted] • Nitrogen oxide (NO x) emissions are measured in many swirled hydrogen flames. • Large-eddy simulations are used to enlighten the formation mechanisms. • Scaling laws for NO x emissions are derived to work for different flame topologies. [ABSTRACT FROM AUTHOR]

The potential solution to hydrogen storage and transportation challenges is provided by liquid fuel-based on-line hydrogen production. An online hydrogen production device has been constructed and the stable output of hydrogen at 6.8 bar under dynamic conditions of 6–13 Nm3/h has been achieved. To achieve optimal economic and thermodynamic performances, the mathematical models for mass, energy, and techno-economics are constructed based on field test data. The Non-Dominated Sorting Genetic Algorithm is employed to update temperature splitting points between multi-stage heat exchangers, targeting multi-objective optimization of heat exchange area, system energy efficiency, and annual average cost. Pareto optimal solutions indicate that such optimization can improve system energy efficiency by 0.03%–3.76% and decrease the hydrogen production cost from 0.004 $/kg to 0.599 $/kg. This work demonstrates the feasibility and effectiveness of multi-objective optimization for online hydrogen production system design and offers important guidance for decision-making in heat exchange network schemes. [Display omitted] • An on-line hydrogen production device based on MSR was established. • The device achieved a stable hydrogen output at 6.8 bar under dynamic conditions. • Mathematical model & multi-objective optimization is investigated for the device. • Solutions with favorable economic and thermodynamic performances were obtained. [ABSTRACT FROM AUTHOR]

Developing electrode materials with improved catalytic activity is inevitable (i) to achieve efficient electro-catalytic water splitting (EWS) and (ii) to construct high performance dye sensitized solar cells (DSSCs). To this aim, Nitrogen (N)-doped carbon-wrapped bimetallic CoCu alloys (i.e, CN@CoCu) are prepared by directly annealing the Cu-loaded Zeolitic Imidazolate Framework-67 (ZIF-67) metal-organic framework (MOF) and employed as (i) working electrode in EWS and (ii) counter electrode (CE) in DSSCs. The ZIF-67 MOF acts as a self-sacrificing template for the formation of CN@CoCu electrodes, whose electro-catalytic activity can be optimized by tuning the Co/Cu molar ratio (Cu = 0, 5%, 10%, 15% and 20%). The addition of 15% of Cu into the ZIF-67 (i.e., CN@CoCu-15), as the working electrode in water splitting has achieved lowest overpotential values of 91 and 256 mV towards hydrogen evolution reaction and oxygen evolution reaction, respectively. Also, for DSSCs applications, the same CN@CoCu-15 sample as CE displays an improved catalytic activity by 21% higher than that of conventional Pt CE towards tri-iodide redox reaction. Consequently, the CN@CoCu-15 based DSSCs device has achieved a PCE of 7.10% which is larger than that of conventional platinum CE (6.69%). The mechanism behind the improved catalytic activity is attributed to the significant reduction in the work function of CN@CoCu-15 (4.82 eV) compared to CN@Co (5.2 eV), as evidenced from Kelvin Probe Force Microscopic analysis. These findings proposed an efficient bifunctional electro-catalytic material with improved water-splitting performance and solar energy conversion. [Display omitted] • Carbon-wrapped CoCu electrode is prepared for water splitting and DSSC application. • The work function of the electrocatalyst is minimum (4.87) when Co/Cu ratio is 15. • It displays excellent catalytic activity towards KOH and triiodide electrolyte. • Water splitting has been achieved at 1.53 V with prepared CN@CoCu-15. • In DSSC, a PCE of 7.10 % is achieved with prepared CN@CoCu-15 as counter electrode. [ABSTRACT FROM AUTHOR]

Due to its ability to reduce emissions in the hard-to-abate sectors, hydrogen is expected to play a significant role in future energy systems. This study modifies a sector-coupled dynamic modeling framework for electricity and hydrogen by including policy constraints, carbon prices, and possible hydrogen pathways and applies it to Texas in 2050. The impact of financial policies, including the US clean hydrogen production tax credit, on required infrastructure and costs are explored. Due to low natural gas prices, financial levers are necessary to promote low-carbon hydrogen production as the optimized solution. The Levelized Costs of Hydrogen are found to be $1.50/kg in the base case (primarily via steam methane reformation production) and lie between $2.10 - 3.10/kg when production is via renewable electrolysis. The supporting infrastructure required to supply those volumes of renewable hydrogen is immense. The hydrogen tax credit was found to be enough to drive production via electrolysis. [Display omitted] • Joint optimization is necessary to show impacts of a sector-coupled hydrogen economy. • Hydrogen from renewable electricity induces immense infrastructure requirements. • Levelized costs in Texas are cost-competitive with other global producers. • Subsidies for renewable energies are required despite decreases in investment costs. [ABSTRACT FROM AUTHOR]

The testing of relay protection devices is an extremely important task on which the stable and safe operation of the power systems depends. One of the most complex and responsible kinds of protection in networks with rotating generation, which includes hydrogen fuel generation, is protection against loss-of-synchronism. Integration of heterogeneous generating electrical devices based on renewable energy sources and based on a hydrogen fuel cell is associated with the need for reliable relay protection. It disconnects tie-lines between the systems in out-of-step conditions. And it is a challenging task to simulate input signals corresponding to the exact settings of the out-of-step protection to make sure it operates correctly. This is because one has to simulate exact parameters of impedance locus (its radius, coordinates of the center in the impedance plane, spin direction, speed, etc.) while available tools embedded in testing devices often don't support such parameters directly. To deal with the problem, the authors present the approach to simulate instantaneous values of line currents and phase-to-ground voltages during the out-of-step operation. These electrical signals form the locus of the impedance vector with the desired parameters to test the operation of the out-of-step protection devices. The software based on the proposed algorithm also provides a graphical representation of the simulation results. All the proposed solutions proved to reduce the time required for commissioning of out-of-step protection and thereby increase tests quality and speed. (provided to the authors on 29.08.2024 for printing in IJHE from the archive of Fermaltech Montenegro Limited, made by A.L. Gusev using Designer. On the DALL E 3 platform.). [Display omitted] [ABSTRACT FROM AUTHOR]

Green hydrogen is a crucial element in the hydrogen value chain, encompassing hydrogen production, transportation, storage, and application. The production of green hydrogen via NaBH 4 hydrolysis (SBH) entails a high cost. However, the fast kinetics of this process with a catalyst compensate for the substantial cost, especially in specific applications, such as local or intermittent use. Silver is known for its excellent catalytic properties. Its high catalytic activity is a key factor in achieving efficient hydrogen generation from (SBH). In this study, a nanocomposite catalyst composed of silver nanoparticles (AgNPs), CoFe 2 O 4 , and carbon nanotubes (CNT) was investigated to demonstrate an effective catalyst design approach to achieve enhanced hydrogen generation performance. The H 2 production rate in the presence of Ag-based/CoFe 2 O 4 –CNT was 320 mL min−1 g−1, and the apparent activation energy was 14.7 kJ mol−1, superior to that of Ag-based catalysts reported in the literature. Analyses of the observed outcomes revealed that the CNT was decorated with well-dispersed AgNPs and CoFe 2 O 4 nanoparticles. The synergistic effects of AgNPs, CoFe 2 O 4 , and CNT were demonstrated by analyzing the kinetic behaviour of each component based on systematic comparisons. Furthermore, the paramagnetic property of CoFe 2 O 4 enables harvesting of the catalyst using an external magnetic field, and it was verified that the reactivity of the collected catalyst was maintained throughout seven successive cycles. The outstanding catalytic performance of Ag/CoFe 2 O 4 – CNT should be attributed to the uniform dispersion of nanoparticles on the CNT surface. Furthermore, our key approach for developing efficient Ag-based carbon advanced catalysts for SBH in the future is to ensure their suitability for industrial applications. Graphical illustration for the hydrogen production by hydrolysis process. [Display omitted] • A magnetic Ag/CoFe 2 O 4 -carbon nanotube nanocomposite was designed and synthesized. • Highly dispersed CoFe 2 O 4 and AgNPs are evenly embedded on the CNT. • Reaction kinetics followed during hydrogen production under different experimental conditions have been investigated. • The ACC catalyst demonstrated high activity, good recyclability, and low activation energy. [ABSTRACT FROM AUTHOR]

Photo‐driven cross‐coupling of o‐arylenediamines and alcohols has emerged as an alternative for the synthesis of bio‐active benzimidazoles. However, tackling the key problem related to efficient adsorption and activation of both coupling partners over photocatalysts towards activity enhancement remains a challenge. Here, we demonstrate an efficient interface synergy strategy by coupling exposed oxygen vacancies (VO) and Pd Lewis acid sites for benzimidazole and hydrogen (H2) coproduction over Pd‐loaded TiO2 nanospheres with the highest photoredox activity compared to previous works so far. The results show that the introduction of VO optimizes the energy band structure and supplies coordinatively unsaturated sites for adsorbing and activating ethanol molecules, affording acetaldehyde active intermediates. Pd acts as a Lewis acid site, enhancing the adsorption of alkaline amine molecules via Lewis acid‐base pair interactions and driving the condensation process. Furthermore, VO and Pd synergistically promote interfacial charge transfer and separation. This work offers new insightful guidance for the rational design of semiconductor‐based photocatalysts with interface synergy at the molecular level towards the high‐performance coproduction of renewable fuels and value‐added feedstocks. [ABSTRACT FROM AUTHOR]

Direct electrochemical seawater splitting is a renewable, scalable, and potentially economic approach for green hydrogen production in environments where ultra‐pure water is not readily available. However, issues related to low durability caused by complex ions in seawater pose great challenges for its industrialization. In this review, a mechanistic analysis of durability issues of electrolytic seawater splitting is discussed. We critically analyze the development of seawater electrolysis and identify the durability challenges at both the anode and cathode. Particular emphasis is given to elucidating rational strategies for designing electrocatalysts/electrodes/interfaces with long lifetimes in realistic seawater including inducing passivating anion layers, preferential OH−adsorption, employing anti‐corrosion materials, fabricating protective layers, immobilizing Cl− on the surface of electrocatalysts, tailoring Cl− adsorption sites, inhibition of OH− binding to Mg2+ and Ca2+, inhibition of Mg and Ca hydroxide precipitation adherence, and co‐electrosynthesis of nano‐sized Mg hydroxides. Synthesis methods of electrocatalysts/electrodes and innovations in electrolyzer are also discussed. Furthermore, the prospects for developing seawater splitting technologies for clean hydrogen generation are summarized. We found that researchers have rethought the role of Cl− ions, as well as more attention to cathodic reaction and electrolyzers, which is conducive to accelerate the commercialization of seawater electrolysis. [ABSTRACT FROM AUTHOR]

Directional electron flow in the photocatalyst enables efficient charge separation, which is essential for efficient photocatalysis of H2 production. Here, we report a novel class of tetracationic cyclophanes (7) incorporating bipyridine Pt(II) and selenoviologen. X‐ray single‐crystal structures reveal that 7 not only fixes the distances and spatial positions between its individual units but also exhibits a box‐like rigid electron‐deficient cavity. Moreover, host–guest recognition phenomena are observed between 7 and ferrocene, forming host–guest complexes with a 1 : 1 stoichiometry. 7 exhibits good redox properties, narrow energy gaps, and strong absorption in the visible range (370–500 nm) due to containing two selenoviologen (SeV2+) units. Meanwhile, the femtosecond transient absorption (fs‐TA) reveals that 7 has stabilized dicationic biradical, efficient charge separation, and facilitates directional electron flow to achieve efficient electron transfer due to the formation of rigid cyclophane and electronic architecture. Then, 7 is applied to visible‐light‐driven hydrogen evolution with high hydrogen production (132 μmol), generation rate (11 μmol/h), turnover number (221), and apparent quantum yield (1.7 %), which provides a simplified and efficient photocatalytic strategy for solar energy conversion. [ABSTRACT FROM AUTHOR]

The photocatalytic hydrolysis reaction primarily unfolds on the material's surface, making the material's morphology and microstructure critical for the catalytic efficiency of photocatalysts. In this paper, a formic acid-assisted melamine hydrothermal self-assembly method is explored to prepare g-C 3 N 4 photocatalysts with a unique morphology. The impact of sintering temperature on the morphology of the g-C 3 N 4 photocatalysts are explored and the effect of formic acid concentration on the XRD and FTIR was analyzed. Findings reveal that the g-C 3 N 4 nanostructures photocatalyst possesses fibrous tubular and nanosheet structures, boasting a heightened specific surface area (32.9 m2/g) and a more refined graphite-like crystalline framework. When synthesized with a 0.15 M concentration of formic acid, the g- C 3 N 4 nanostructured photocatalyst achieved a hydrogen production rate (1289.4 μmol h−1 g−1), which is approximately 4.8 times greater than that of bulk g-C 3 N 4 (264.7 μmol h−1 g−1). This work provides a simple method for preparing high-performance g-C 3 N 4 based photocatalysts for visible light hydrolysis hydrogen production. [ABSTRACT FROM AUTHOR]

Bringing floating offshore wind turbines (FOWTs) to a real industrial maturity and reducing the levelized cost of floating wind energy are key to significantly increasing the penetration of renewables in the energy mix of Mediterranean countries, especially if in combination with suitable energy storage systems, such as those involving green hydrogen production. The present study analyses techno‐economic aspects of some of the technologies related to FOWTs and hydrogen production by means of offshore‐generated energy, aiming to evaluate the potential of a floating wind farm integrated with a power‐to‐gas energy storage system in a specific installation site near the Sardinian shores. In comparison to the pioneering studies to date, a more detailed computational model is used, able to account for several critical factors like a better description of metocean conditions, constraints on grid capacity, and a state‐of‐the‐art model to define the farm layout. Concerning hydrogen production, a comparison between the statistical approach, which is commonly used in the field, and a fully time‐dependent method is performed. Proposed results obtained with the statistic and the time‐dependent approach show values ranging between 3.79 and 5.47€/kg, respectively. These outcomes are thought to provide an interesting comparison between different fidelity approaches and realistic reference values for the levelized cost of hydrogen by floating wind in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Eight scenarios where high efficiency reversible solid oxide cells (rSOC) are combined with an offshore wind farm are identified. Thanks to the PyPSA power system modelling tool combined with a sensitivity study, optimized rSOC system capacities, hydrogen storage capacities, and subsea cable connection capacities are investigated under various combinations of rSOC system capital cost, prices paid for hydrogen, and electricity prices, which give indications on the most profitable scenario for offshore hydrogen production from a 600 MW wind farm situated 60 km from shore. Low electricity prices (yearly average 45 £/MWh) combined with mild fluctuations (standard deviation 6 or 13 £/MWh) call for dedicated hydrogen production when the hydrogen price exceeds 4 £/kg. High electricity prices (yearly average 118 or 204 £/MWh), combined with extreme fluctuations (standard deviation between 73 and 110 £/MWh), make a reversible system economically profitable. The amount of hydrogen which is recommended to be reconverted into electricity depends on the price paid for hydrogen. Comparison of the optimized cases to the default case of a wind farm without hydrogen production improved profit by at least 3% and up to 908%. Comparison to the default case of dedicated hydrogen production, showed that in the case of low hydrogen prices, an unprofitable scenario can be made profitable, and improvement of profit in the case of a profitable default case starts at 4% and reaches numbers as high as 324%. [ABSTRACT FROM AUTHOR]

The development of hydrogen energy is widely recognized as a key approach to addressing the energy and carbon emission challenges. Methanol steam reforming is a promising hydrogen production scheme that can provide high-purity hydrogen. In this work, we studied the primary reaction mechanisms of methanol steam reforming over the Cu(111) and Cu(211) surfaces using density functional theory (DFT) calculations and microkinetic simulations. A detailed kinetic perspective on the reaction mechanism, which is often overlooked in previous research that relies solely on DFT calculations, is provided in the current work. Our findings reveal that under typical experimental conditions, the dominant mechanism on the Cu(111) surface is the methyl formate mechanism, while the H2COO dehydrogenation mechanism is dominant on Cu(211). The activity over the Cu(111) surface was slightly higher than that over Cu(211). Based on the degree of rate control analysis results, a reaction rate equation was derived to quantitatively explain the trend of activity under different operating conditions. It was also found that CO2 selectivity was significantly higher over Cu(211) than over the Cu(111) surface. Furthermore, based on the Wulff construction scheme, copper nanoparticle models with different sizes were constructed, and a detailed structure sensitivity study was executed. This comprehensive investigation sheds light on the mechanisms of methanol steam reforming reactions over the Cu(111) and Cu(211) surfaces, providing essential insights for the design of high-performance catalysts for hydrogen production. [ABSTRACT FROM AUTHOR]

The fabrication of diluted magnetic semiconductors (DMSs) for spintronic devices has garnered significant recognition due to their diverse and impressive applications. Additionally, addressing global warming, replacing fossil fuels, and providing green energy are critical challenges of our time. In this context, we synthesized and characterized Sm-doped CdS nanoparticles, examining their magnetic, optical, structural, and photocatalytic hydrogen evolution properties for both spintronic and hydrogen fuel production applications. Structural analysis revealed that Sm ions successfully substituted Cd sites without altering the original structure. Optical studies demonstrated a reduction in the band gap with the incorporation of Sm ions into the CdS lattice, thereby enhancing the visible light absorption capabilities of the samples. Room temperature magnetic measurements indicated that while pristine CdS is paramagnetic, Sm-doped CdS nanoparticles exhibit strong ferromagnetic properties due to double exchange interactions among available spins, making them ideal for spintronic applications. Photocatalytic water splitting tests demonstrated that the CdS(4 at%) system achieved the highest hydrogen evolution rate among the samples, reaching 1629 μmol/g. We believe the CdS(4 at%) system is a promising candidate for efficient hydrogen fuel production under simulated sunlight irradiation, contributing to clean, renewable energy production. [ABSTRACT FROM AUTHOR]

This work combines the nanoconfined material with the air-breathing gas diffusion electrode equips a wide practical range of applications for the synthesis of high-yield H 2 O 2 and upgrading of H 2 O 2 products. [Display omitted] • Yolk-shell SnS 2 @CSs Z-scheme nanoreactor is controllably synthesized. • Hydrogen peroxide production is increased through the nano-confinement effect. • Continuous hydrophobic layers allow air to spontaneously diffuse into the AGPE. • The photoelectrode has a good reusability and stability for activation of O 2 /H 2 O. • Hydrogen peroxide is produced under neutral condition media. The diffusion and adsorption properties of the O 2 /H 2 O corpuscles at active sites play a crucial role in the fast photo-electrocatalytic reaction of hydrogen peroxide (H 2 O 2) production. Herein, SnS 2 nanosheets with abundant interfacial boundaries and large specific areas are encapsulated into hollow mesoporous carbon spheres (CSs) with flexibility, producing a yolk-shell SnS 2 @CSs Z-scheme photocatalyst. The nanoconfined microenvironment of SnS 2 @CSs could enrich O 2 /H 2 O in catalyst cavities, which allows sufficient internal O 2 transfer, improving the surface chemistry of catalytic O 2 to O 2 − conversion and increasing reaction kinetics. By shaping the mixture of SnS 2 @CSs and polytetrafluoroethylene (PTFE) on carbon felt (CF) using the vacuum filtration method, the natural air-breathing gas diffusion photoelectrode (AGPE) was prepared, and it can achieve an accumulated concentration of H 2 O 2 about 12 mM after a 10 h stability test from pure water at natural pH without using electrolyte and sacrificial agents. The H 2 O 2 product is upgraded through one downstream route of conversion of H 2 O 2 to sodium perborate. The improved H 2 O 2 production performance could be ascribed to the combination of the confinement effect of SnS 2 @CSs and the rich triple phase interfaces with the continuous hydrophobic layer and hydrophilic layer to synergistically modulate the photoelectron catalytic microenvironment, which enhanced the transfer of O 2 mass and offered a stronger affinity to oxygen bubbles. The strategy of combining the confined material with the air-breathing gas diffusion electrode equips a wide practical range of applications for the synthesis of high-yield hydrogen peroxide. [ABSTRACT FROM AUTHOR]

[Display omitted] Piezocatalysis has emerged as a sustainable alternative for hydrogen peroxide production. However, the current development of efficient piezocatalysts is predominantly focusing on those conventional piezoelectric ceramic oxides with high permittivity and limited catalytic activities. Therefore, innovative approaches to develop novel piezocatalysts in particular from these outstanding paraelectric semiconductors are highly required. In this work, by employing a feasible doping strategy, robust piezoelectric property is created on the Ba 2 Nb 2-x Fe x O 6-δ double perovskite oxides, typically characterized by a stable paraelectric cubic structure. Optimum Fe doping not only intensifies the double perovskite phase but also inspires a phase transition from a centrosymmetric cubic to a piezoelectric tetragonal phase, thereby achieving desirable piezoelectricity and enabling a series of favorable physical properties including redox activity, active sites of anion defects, reduced bandgap, and increased free charge density. All these are important factors to enhance piezocatalytic activity. As a result, Ba 2 NbFeO 6-δ achieved by the optimum Fe doping demonstrated exceptional piezocatalytic H 2 O 2 yield of 512 and 690 µmol g-1 h−1 under atmosphere and oxygen-purging conditions, respectively, without the presence of any sacrificial agents. Mechanistic investigations reveal that both water oxidation and oxygen reduction involve in the H 2 O 2 production, wherein piezopotential plays a critical role not only in facilitating the charge carrier separation and transportation but also in modulating the band structure to enhance the catalyst redox capacity. This study offers a feasible and universal strategy for the design of novel piezocatalysts, expanding the windows for catalyst selection for piezocatalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dip-coated GO on NF was in situ reduced and N -doped by N 2 plasma method. • PNrGO as the conductive substrate endowed NiCo-LDH growth. • NiCo-LDH@PNrGO/NF was employed as the redox mediator for decoupled water electrolysis. • Redox mediator exhibited high electrochemical capacitance and buffering capacity. Although the recent emergence of decoupled water electrolysis prevents typical H 2 /O 2 mixing, the further development of decoupled water electrolysis has been confined by the lack of reliable redox mediator (RM) electrodes to support sustainable H 2 production. As energy storage electrodes, layered double hydroxides (LDHs) possess inherently poor conductivity/stability, which can be improved by growing LDHs on graphene substrates in situ. The proper modification of the graphene surface structure can improve the electron transport and energy storage capacity of composite electrodes, while current methods are usually cumbersome and require high temperatures/chemical reagents. Therefore, in this study, dip coating was adopted to grow graphene oxide (GO) on nickel foam (NF). Then, the GO was reduced using nonthermal plasma (NTP) to reduced GO (rGO) in situ while simultaneously implementing N doping to obtain plasma-assisted N -doped rGO on NF (PNrGO/NF). The uniform conductive substrate ensured the subsequent growth of less-aggregated NiCo-LDH nanowires, which improved the conductivity and energy storage capacity (5.93 C/cm2 at 5 mA/cm2) of the NiCo-LDH@PNrGO/NF. For the decoupled system, the composite RM electrode exhibited a high buffering capacity for 1300 s during the decoupled H 2 /O 2 evolution, and in the conventional coupled system, the necessary input voltage of 1.67 V was separated into two lower ones, 1.42/0.33 V for H 2 /O 2 evolutions, respectively. Simultaneously, the RM possessed outstanding redox reversibility and structural stability during long-term cycling. This work could offer a feasible strategy for using NTP to synthesize excellent RM electrodes for application to decoupled water electrolysis. [ABSTRACT FROM AUTHOR]

Electrocatalysis can synthesize kinds of valuable chemicals and plays vital role in developing clean and renewable energy storage and conversion devices. In the traditional electrocatalytic systems, researchers try to synthesize one type of valuable chemical at cathode or anode independently. Recently, electrocatalytic bipolar synthesis of valuable chemicals at both cathode and anode simultaneously becomes popular and attracts much attention. In this minireview, we summarize the latest processes on innovative strategies for electrocatalytic bipolar synthesis of various chemicals. We will discuss the findings according to the categories of the products, including bipolar hydrogen production, bipolar formate production and bipolar hydrogenation. And the associated catalysts optimization, reaction mechanism, and design principles are well introduced. Moreover, the challenges and prospects are highlighted for future developments. This review is timely and will guide others pay more attention to this novel electrocatalytic bipolar synthesis systems. [ABSTRACT FROM AUTHOR]

Hydrogen energy with a high fuel value is considered to be one of the most important renewable and clean energy sources in sustainable energy. Electrocatalytic water splitting is the best way to produce hydrogen sustainably on a large scale. In this work, the sand rose‐like MoSe2/NiSe/NiFe layered double hydroxide (NiFe‐LDH) catalyst is obtained by a two‐step hydrothermal method for hydrogen evolution (HER) and oxygen evolution reaction (OER). The three‐dimensional (3D) hierarchical structure is observed by SEM, TEM, XRD and XPS, and the results showed that there is strong electronic interaction among the components, which promotes electron transfer and improves catalytic activity. In the alkaline environment, the catalyst exhibits excellent HER and OER performance, the current density of 10 mA cm−2 requires only 130 mV and 136 mV overpotential, respectively. In the water splitting system composed of MoSe2/NiSe/NiFe‐LDH as both cathode and anode, only 1.51 V voltage reaches the current density of 10 mA cm−2, and workes continuously for more than 120 h at 100 mA cm−2 current density with excellent stability. The Faraday efficiency of hydrogen production is close to 100 %. This study provides a promising strategy for the preparation of efficient electrocatalyst for overall water splitting. [ABSTRACT FROM AUTHOR]