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Carbon paper (CP) used for proton exchange membrane fuel cells (PEMFCs) are improved using carboxyl-terminated butadiene-acrylonitrile (CTBN)-modified phenolic resin (PF) for impregnation of CP preform. The effect of CTBN ratio on the properties of CP, which is fabricated by the processes of impregnation, molding and heat treatment, is investigated. The results show that compared with the CP without CTBN addition, the CTBN-modified CP exhibits significantly improved overall properties. With the increase of CTBN ratio in the mixture, porosity and permeability of the modified CP increase because of the low carbon yield of CTBN after heat treatment. Mechanical strength and conductivity also increase because of the chemical reactions between the CTBN and resin that lead to robust interfacial bonding in the CP product. However, excessive CTBN addition causes decreased tensile and bending strength of the CP. Single cell tests show that the increased conductivity of the CP enhances the polarization performance in the Ohm polarization region, while the CTBN-induced nearly spherical micro/macro-pores in the CP matrix improve the performance in the concentration polarization region. At an optimum CTBN ratio of 50 wt%, the membrane electrode assemble with the modified CP exhibits a current density of 1606.5 mA cm −2 at 0.608 V. [ABSTRACT FROM AUTHOR]

A layered binary Mn-Fe oxide as bi-functional electro-catalyst with nanopetals morphology is grown on porous carbon paper for the first time via one-step electrodeposition process. The electrocatalyst is characterized by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive spectroscopy analysis. SEM analysis demonstrates notable morphology viz. nanopetals of the Mn-Fe oxide grown on carbon paper. The electrocatalytic activity is checked for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline medium. Rotating disk electrode (RDE) voltammetry is carried out to study the ORR kinetics, which proves that ORR process follows four-electron pathway in alkaline medium. Oxygen evolution reaction study reveals that it has higher activity for OER with a lower onset potential of 1.6 V vs RHE and higher current density of 11.5 mA/cm 2 at 2.0 V vs RHE reference electrode. [ABSTRACT FROM AUTHOR]

Titanium dioxide is emerging as new class of catalyst support for fuel cell reactions. Via pulsed laser deposition, we prepare hierarchically organized and vertically aligned TiO 2 /Pt nanostructured films on microfibrous carbon paper (CP) substrate at room temperature. Microstructural analyses reveal a metal-support interaction between TiO 2 and Pt. Namely; (i) the particles size of Pt on TiO 2 is smaller than those of Pt grown onto carbon paper substrate under similar condition of synthesis and (ii) Pt metallic state is transformed to ionized Pt 2+ and Pt 4+ . Compared to CP/Pt electrocatalyst, the CP/TiO 2 /Pt electrocatalysts (i) oxidize ethanol at much lower potentials, (ii) display superior current peak densities of more than 2.5 times higher by voltammetry, and (iii) steady state current density during long-term stability up to 8 times greater. For portable electronic applications, the binder-free and hierarchical structures of the CP/TiO 2 /Pt electrocatalyst with its planar deposition make it very attractive as anode for direct ethanol fuel cells. [ABSTRACT FROM AUTHOR]

The performance of proton exchange membrane fuel cell (PEMFC) is greatly influenced by the characteristics of gas diffusion layer (GDL). Herein, in situ grown carbon nanotubes (CNTs) on carbon paper as a gas diffusion layer (GDL) were fabricated by a plasma-enhanced chemical vapor deposition (PECVD) process. Fuel cells using CNT-based GDLs with nickel (II) nitrate loading of 1.6 mg cm −2 show better performance compared with the GDLs which employ Vulcan XC-72 as the MPL. The pore size distribution and the gas permeability results revealed that the increasing density of CNT layer had two main effects on the pore structure of GDL: firstly, the increasing density of CNT layer decreased the macro pore volume and the open through pore volume of CNT-based GDL; secondly, the increasing density of CNT layer decreased the micro pore diameter of CNT-based GDL. The data obtained from the vapor permeability and the fuel cell performance tests indicated that the water flooding can be reduced by applying CNT-based GDLs. The electrochemical impedance spectroscopy (EIS) confirmed that the CNT-based GDL can effectively promote the mass transfer in the FCs which was attributed to its suitable hydrophobicity and proper structure. [ABSTRACT FROM AUTHOR]

The development of non-precious metal catalysts exhibiting high performance towards both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) has been recognized as one of the ultimate goals in water electrolysis research. Herein, we report on the synthesis of an efficient OER and HER catalyst, NiFe/MoO 3 @CFP, using a unique synthetic technique that combines ultrasonic synthesis and electrochemical deposition. The Mo-based compound, used as a template for the NiFe structure, was formed during the ultrasonication, and cavitation bubbles generated via ultrasonication were found to play a key role for improving the catalyst performance. NiFe/MoO 3 @CFP achieved a current density of 20 mA cm−2 for the OER and HER at low overpotentials of 251 and 204 mV, respectively. It was found that a cell potential of 1.589 V was required to achieve 10 mA cm−2 in the overall water splitting process. This study presents the effective preparation of a catalyst using ultrasound technology, which has rarely been used, suggesting its potential for future applications. • NiFe/MoO 3 @CFP was prepared by electrochemical deposition and ultrasonic synthesis. • Ultrasonic synthesis lowered the charge transfer resistance of the catalyst. • NiFe/MoO 3 @CFP showed low overpotentials of 251, 204 mV for the OER and HER (η 20). [ABSTRACT FROM AUTHOR]

Carbon/germanium dioxide (C/GeO 2 ) paper-like self-supporting membranes to be used as binder- and collector-free anodes in flexible Li-ion batteries (LIBs) are synthesised via electrospinning (ES) followed by stabilisation and carbonisation heat treatments. Carbonisation is operated at relatively low temperature (550 °C) in order to keep high nitrogen concentration in the carbonaceous fibre network, which is claimed to be beneficial for Li-ion storage. Regardless of the germanium load in the spinnable solution (2.50–4.25 wt%), α-quartz GeO 2 nanoparticles (NPs) encapsulated in highly N-doped (10–16 at%) C fibres are produced. The size of the oxide NPs and the fibre diameter increase with increasing germanium load. Based on the results of the compositional analysis, the specific capacities of the composite fibres are expected to range between 590 and 780 mAh/g. Preliminary results of half-cell tests substantially confirm the expectations, with Coulombic efficiencies of 92–96% at the second charge/discharge cycle. [ABSTRACT FROM AUTHOR]

In order to improve the hydrogen sensing of transition metal oxide nanomaterials at room temperature, MoO 3 nanowire paper was prepared and used as a hydrogen sensing materials on substrate. In this paper, orthorhombic phase, ultra-long (∼1 mm) MoO 3 nanowires were synthesized through conventional hydrothermal method at 260 °C for 96 h. A flexible nanowires paper with size of 200 mm × 300 mm was obtained by further self-assembly formation process of pure α-MoO 3 nanowires in aqueous solution on hydrophobic substrate, and the thickness of paper can be controlled depend on the concentration of disperse nanowires. A novel hydrogen sensor with sensing area of 10 mm × 10 mm was obtained after Pt interdigital electrodes (IDE) deposited on the surface of α-MoO 3 nanowires paper and transferred into ceramic circuit board (CCB) without any surface modification. The response and recovery time are about 3.0 and 2.7 s toward 1.5% H 2 , respectively. The sensors also show good selectivity toward H 2 against other reduce gas, such as C 2 H 5 OH, CO and CH 4 . Large amounts of the porous structures and high specific surface of nanowires paper is beneficial to the absorption of oxygen molecules, which would lead to the high sensitivity, fast response and recovery speed of sensor at room temperature. MoO 3 nanowires paper sensors have excellent stability and reliability, which could work for 5.56 years at room temperature. [ABSTRACT FROM AUTHOR]

A 3D multiphase lattice Boltzmann model (LBM) was established and employed to study the impact of polytetrafluoroethylene (PTFE) content and distribution on the liquid–gas transport in proton exchange membrane fuel cell (PEMFC) carbon-paper gas distribution layer (GDL). In the computer-generated carbon paper GDL, part of the fibers’ surface was randomly specified as PTFE to achieve a desired PTFE content and distribution. For non-uniform PTFE distribution cases, a GDL sub-region neighboring to gas channel (GC) was set to have higher PTFE content. PTFE content and distribution show important influence on the liquid–gas flow and on the relationship of relative permeability versus phase saturation. The GDL sub-region of more PTFE acts like a capillary barrier and raises the liquid saturation level in the rest part of GDL. The simulated liquid saturation level in GDL diminishes with the increase of PTFE content in GDL. The liquid phase relative permeability is larger in the GDL of lower PTFE content if the (overall) liquid saturation is lower than a threshold value, whereas it becomes smaller if the liquid saturation is higher than this threshold value. The liquid phase relative permeability in the GDL with non-uniform PTFE distribution is reduced when the liquid saturation in GDL is lower than a certain value, but when the liquid saturation is higher than this value, it is larger compared with that in the GDL with uniform PTFE distribution. The gas phase relative permeability in the GDL of lower PTFE content is larger than tat in the GDL of higher PTFE content and the non-uniform distribution of PTFE in GDL slightly reduces the gas phase relative permeability value. [ABSTRACT FROM AUTHOR]

This review paper explores into the extensive realm of alkaline water electrolysis (AWE), a transformative technology for hydrogen production, offering profound insights and future prospects for sustainable growth. It embarks on this journey by explaining the fundamental principles, the application of Faraday's laws, electrolyzer design, and the intricate electrochemical processes transpiring at the cathode and anode. Subsequently, it investigates electrode materials, catalysts, membrane material and their recent developments, unveiling essential aspects of material selection and performance enhancement. The exploration extends to the domain of alkaline electrolyte solutions, where it provides a comprehensive overview of common electrolytes, the impact of concentration on system performance, and pioneering research on alternative electrolytes. Shifting focus towards large-scale systems and industrial applications, the paper unravels the economic feasibility, considerations regarding costs, and the transformative influence of alkaline water electrolysis on diverse industries. The final segment is dedicated to emerging trends and future directions. It casts light on recent breakthroughs and the potential for commercialization, presenting a vivid image of the evolving role of this technology in the sustainable energy landscape. The conclusive segment, this review offers a recapitulation of the key discoveries and insights presented throughout the paper, while delivering a critical evaluation of the present state of alkaline water electrolysis. It emphasizes the potential of the technology while recognizing critical research areas such as electrode materials, safety standards, scaling efficiency, flexible operation, and surface modification techniques. In the rapidly changing energy scenario, this paper stands as a testament to the dynamic nature of alkaline water electrolysis and its pivotal role in a sustainable energy future. • Identifying different alkaline water electrolysis (AWE) cell efficiencies and transport resistances. • Insights into recent development in electrodes, catalysts, and separator membranes materials. • Recognizing recently examined alkaline electrolytes. • Recent and emerging trends in AWE including the use of electromagnetic field and pulsating potential. • Perspectives of scaling up AWE and its industrial commercial applications. [ABSTRACT FROM AUTHOR]

This paper investigates a downdraft multi-injection moving bed reactor (MBR) for the hydrolysis reaction in the copper-chlorine (Cu–Cl) thermochemical cycle for hydrogen production. The numerical modelling is conducted for a variety of system configurations of the MBR, with a focus on reducing the energy requirement of the reactor while achieving high conversion rates. Several design variables are investigated, including reactor volume, injection point location, and quantity of steam injection. The numerical predictions show an approximate 23% increase in CuCl 2 conversion for the multi-injection MBR compared to a single injection design. A maximum conversion of 66.5% is predicted through design parameter variations. Asymptotic behavior for the quantity of injection locations with respect to conversion extent is presented for several different steam to copper ratios. The results and new insights in this paper suggest opportunities for conversion improvement and steam to copper ratio reduction in the hydrolysis reactor through the MBR design. • Multi-injection moving bed hydrolysis reactor simulated with a kinetic model. • Investigates reactor designs/operating conditions for better hydrolysis efficiency. • 23% increase in CuCl 2 hydrolysis conversion through multi-injection MBR model. • Identified maximum hydrolysis conversion asymptote with steam injection quantity. [ABSTRACT FROM AUTHOR]

Green hydrogen can be the transitional solution required to reduce anthropogenic emissions and enhance energy independency from fossil fuel. To improve green hydrogen adoption, a cluster-based infrastructure, called a hydrogen hub, is devised taking into account the demand-supply interplay coupled with transport ease. In this paper, we have identified sites across states that are conducive for hydrogen hubs. It involves a multicriteria decision-making (MCDM) framework deployed to assign priorities within competing set of criteria. A comprehensive analytical hierarchy process (AHP) is used to rank criteria that are connected to establish a functioning hydrogen hub. These criteria include, but not limited to, proximity to refineries, fertilizer plants, substations, chlor-alkali units, steel manufacturing plants, water availability, access to gas pipelines, railway line access, and finally distance to highways. Our analyses indicate that proximity to refineries and fertilizers scored higher (scores directly proportional to importance) while railway line access scored the least. These prioritised scores are used to spatially locate sites using geographical information system. In a total of thirteen states identified, Gujarat had the largest parcel of most suitable land for setting up hydrogen hub followed by Maharashtra and Andhra Pradesh. For India to set up a functioning hydrogen economy and achieve green hydrogen goals, it is important to identify states that can drive the agenda forward. This paper illustrates a way (amongst many available ways) to identify states based on their strength and capability to fulfil the national goal of 5 million tons of green hydrogen by 2030. • The paper addresses setting up of green hydrogen hubs in India based on a multi-criteria site selection framework. • Nine selection criteria covering aspects of hydrogen ecosystem proposed to identify site(s) suitable for hydrogen hubs. • Integration of AHP and GIS is used to ascertain land parcels where hydrogen economy can sustain across states in India. • Zones in 13 states were identified as potential hydrogen hubs. [ABSTRACT FROM AUTHOR]

Utilization of agricultural and food wastes for biohydrogen generation is a hot research topic. In this paper, biohydrogen generation potentials from wheat, maize, barley, rice and potato production, consumption, associated losses, and household food waste generation in Turkey is estimated till 2030 using novel semi-empirical holistic models based on different scenarios. It was estimated that up to 90 thousand tonnes of biohydrogen could be produced from household food wastes in Turkey in 2030. This amount of biohydrogen would be worth 1.5 billon US$ and generate nearly 0.8 billion US$ of net return. In addition, this study clearly shows that there is a great potential for economic gain from agricultural and food waste based biohydrogen generation in Turkey. In conclusion, the methodology developed in this study could be used by researchers around the world to estimate local and national level biohydrogen generation potentials from agricultural and food wastes. [Display omitted] • This paper examines biohydrogen potentials from agricultural and food wastes. • Holistic per capita models for estimating annual biohydrogen production potentials. • Annual production and sale costs are estimated. • Annual net returns from biohydrogen generation are calculated. • The results highlight recommendations for future research directions. [ABSTRACT FROM AUTHOR]

In order to meet rapidly growing demand of liquid hydrogen in the future hydrogen industry and energy structure, the continuous catalytic ortho-para hydrogen conversion technology (CCOPHCT) has been once again proposed and has become an important choice to improve the hydrogen liquefaction units (HLUs). The origin, concept, and research progress of the CCOPHCT are systematically reviewed for the first time in this paper. However, the research depth and breadth of the CCOPHCT are insufficient to support its current application. To solve it, for the continuous catalytic ortho-para hydrogen conversion plate-fin heat exchanger (CCOPHC-PFHE) with better comprehensive performances, this paper comprehensively summarizes the research achievements in the related fields from the perspective of the unit analysis, including the ortho-para hydrogen conversion (OPHC), packing layer and plate-fin heat exchanger (PFHE), which to provide further thinking for the development of the CCOPHC-PFHE. Further, some suggestions for the CCOPHCT are proposed based on the existed research foundations, including preparing the effective ortho-para hydrogen conversion catalyst (OPHCC), developing the accurate OPHC dynamical model, revealing the coupling mechanism in the packing layer filled with the OPHCC and establishing an effective design method and standard of the CCOPHC-PFHE. In addition, considering the special conditions on the CCOPHC-PFHE, the importance of the experimental research is emphasized. And based on the established hydrogen experimental platform with the comprehensive supporting implementations, the experimental device of the CCOPHC-PFHE has been completed and a series of experimental tests are currently in progressing. [Display omitted] • The origin, concept, and progress of the CCOPHCT are reviewed for the first time. • The CCOPHC-PFHE is the preferred choice for the CCOPHCT. • The related researches are summarized to give a further thinking for the CCOPHC-PFHE. • Some suggestions are proposed for the further development of the CCOPHC-PFHE. • The experiment on the CCOPHC-PFHE is essential and currently in progressing. [ABSTRACT FROM AUTHOR]

As the global shipping industry experiences rapid expansion, the imperative to address greenhouse gas emissions and environmental impact becomes increasingly paramount. Hydrogen has emerged as a pivotal and eco-friendly energy source, offering a pathway towards carbon neutrality and a complete zero-carbon transition in maritime operations. However, the widespread adoption of hydrogen-powered ships hinges on the establishment of robust regulations and technical standards. This paper conducts a comprehensive examination of hydrogen fuel cell (FC) technology in ships, scrutinizing the role of international classification societies and exploring existing standards and regulations within the maritime industry, specifically centered around hydrogen energy. The study outlines a strategic developmental roadmap for a green shipping hydrogen energy system tailored for hydrogen FC-powered ships in China. Emphasizing the differences in hydrogen application between fuel cell vehicles and ships, the paper elucidates technical challenges unique to hydrogen FC-powered ships. Furthermore, it proposes a visionary framework for future technical standards, advocating for the creation of a ship-based hydrogen energy standard system, the development of core technical standards, and a heightened focus on safety regulations. Through comprehensive analysis and compelling argumentation on hydrogen fuel cell ship technology and standards, this paper underscores the indispensable role that technical standards play in propelling the advancement of environmentally friendly shipping. Beyond serving as an informative resource, the paper aims to provide valuable guidance and direction for the future demonstration, application, and promotion of hydrogen fuel cell ship technology. Ultimately, it underscores the pivotal role of technical standards in advancing sustainable maritime transportation. • Analyze hydrogen energy technical standards from the production, storage, safety. • Comparison of hydrogen energy technical differences between vehicles and ships. • Outline the unique challenges of applying hydrogen technology to ship operations. • Constructed a technical standard framework for future hydrogen energy ships. [ABSTRACT FROM AUTHOR]

Electrolysis of water for production of hydrogen has become one of the most fascinating methods to relieve the energy crisis and environmental pollution. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam through a two-step hydrothermal process, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. Under an alkaline condition of 1 M KOH, Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2, and using Co–NiS/Mo 2 S 3 as both cathode and anode, only the potential of 1.574 V is required to drive a current density of 50 mA cm−2, with a relatively good durability over 15 h. Density functional theory (DFT) analysis show that the ΔG H* of Co–NiS is closer to 0 and its density of states near the Fermi energy level is higher, suggesting that Co–NiS improves the electrical conductivity of Co–NiS/Mo 2 S 3 and plays a significant catalytic action. This work proposes novel insights for the future exploration of novel sulfur-based composite electrocatalysts with excellent HER performance. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam by a two-step hydrothermal method, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. [Display omitted] • M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials were successfully synthesized by hydrothermal processes. • Co–NiS/Mo 2 S 3 electrode shows excellent catalysis in the cathode reaction of water and water electrolysis. • Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Microbial electrolysis cells (MECs) are emerging sustainable power generation technologies that can be used for biohydrogen production and wastewater treatment. The prospect for hydrogen gas as a vehicle fuel suitable for the environment is enormous. MEC serves as a reactor for producing biohydrogen by mixing MFC with electrolysis. MECs are the most sustainable, clean, and effective ways to produce biohydrogen. Effective aspects impacting H 2 production, including microbial culture, electrodes, membrane, and substrate, have been explored for greater comprehension of creating MEC technology-based hydrogen generation. The present issues with effective scale-up include the costly production expenses of microbial electrolysis cells, their significant internal resistance, methanogenesis, and membrane/cathode biofouling. This review examines the various operational parameters in optimization studies that influence overall hydrogen generation. This paper also presents strategies to overcome the constraints listed above by creating effective architecture, including several reactor designs, biological, and physical properties, and the use of various operational conditions for improved hydrogen production. This study summarizes recent developments and several other operating factors (organic loading, ionic strength, hydraulic retention time, applied voltage, etc.) that affect hydrogen production in an MEC system. The paper outlines the present technical difficulties and offers practical future ideas for addressing the constraints. [Display omitted] • MEC has great efficiency in hydrogen recovery and concurrent waste conversion. • Microbial culture, electrodes, membrane, and substrate affect H 2 production in MEC. • Scale-up constraints: high costs, internal resistance, methanogenesis, and biofouling. • Modifying strain, nanoparticles, and reactor design can help in overcoming this. [ABSTRACT FROM AUTHOR]

Locomotive engines serve as the powering heart of rail transportation which is widely used for massive cargo over long distances. The traditional locomotive engines have depended on the internal combustion engine for decades, operated using fossil fuels that negatively impact the environment. Since more and more commodities are transported by trains, the prime engines need to be improved where the fuels are expected to enhance the engine's performance and alleviate the environmental impact. This paper presents a comparison of three developed locomotive engines with different configurations, such as an internal combustion engine combined with a gas turbine and molten carbonate fuel cell (ICE-GT-MCFC), a gas turbine combined with a solid oxide fuel cell and onboard hydrogen production using aluminum electrolysis cell (GT-SOFC), and a GT combined with sold oxide and proton exchange membrane fuel cells (GT–SOFC–PEMFC). The paper then identifies one hybridized engine, which is GT–SOFC–PEMFC, according to its low weight and better performance to conduct an optimization study to enhance its efficiency, reduce the cost, and lower the environmental impact. The present optimization study is undertaken through a multi-objective particle swarm optimization, involving thermodynamic, exergoeconomic, and exergoenvironmental analyses. The optimized GT–SOFC–PEMFC locomotive engine is improved in power from 5.9 MW to 7.3 MW and improved in performance to 49.1% energetic efficiency and 47.0% exergetic efficiency. Additionally, the optimized GT–SOFC–PEMFC engine has less specific fuel and product cost of 24.9 $/GJ and 34.7 $/GJ, respectively, and less specific exergetic environmental impact of fuel and product of 13.2 Pt/GJ and 16.2 Pt/GJ, respectively. Also, the relative cost difference and relative environmental impact difference are significantly reduced by more than 20% to 39.4% and 22.8%, respectively. The operational conditions of the optimized GT–SOFC–PEMFC engine are improved to achieve better efficiency and better cost effectiveness in a more environmentally-benign manner. • Comparison between three hybridized combined locomotive engines is established. • Optimized GT–SOFC–PEMFC engine has 7.3 MW power and 49% energetic efficiency. • Specific exergetic product cost declined to 51 $/GJ for fuel and 35 $/GJ. • Specific exergetic environmental impact for fuel and product becomes 13 and 16 Pt/GJ. • The relative environmental impact difference becomes 22.8% instead of 44.3%. [ABSTRACT FROM AUTHOR]

Hydrogen is a kind of clean renewable energy with great development potential. However, traditional electrocatalytic water splitting methods often require high energy consumption and expensive catalysts, which limits their practical application. Transition metal selenides (TMSes), as a new type of hydrogen production materials from electrolytic water, have been the focus of research in recent years. The basic principle of electrochemical water cracking and the preparation of TMSes are reviewed in this paper. The electrocatalysts for hydrogen evolution, oxygen evolution and integral water cracking based on TMSes, including single metal selenides, binary metal selenides, and multinary mixed metal selenides, are discussed. Finally, the future research direction and the development prospect of TMSes electrocatalysts are prospected. • Eley-Rideal and Langmuir-Hinshelwood mechanisms were used to analyze the OER reaction mechanism. • The production and properties of transition metal selenides in recent years are introduced in detail. • In this paper, transition metal selenides are introduced from single TMSes, binary TMSes and multinary mixed TMSes. • The physical properties and electronic structures of transition metal selenides are described in detail. [ABSTRACT FROM AUTHOR]

This study presents a bibliometric review focusing on the utilization of water electrolysis as a means of generating hydrogen as an energy carrier. The analysis includes research conducted over the past decade, covering from 2014 to 2023 (till August). Several key aspects are highlighted, including publication trends, the leading country in research output, journal rankings, and a citation analysis of papers related to water electrolysis. The findings reveal a notable increase in publication trends, with China emerging as the leading contributor in this research area. Furthermore, the International Journal of Hydrogen Energy is identified as the highest-ranked journal in terms of both publication number and citation impact. Additionally, the top ten most cited research articles and review papers are investigated to determine their influence within the field. To gain a deeper understanding of water electrolysis methods, the three primary approaches: alkaline water electrolysis (AWE), proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis (SOE) is examined. The analysis emphasizes that PEM electrolysis is the most prevalent method for hydrogen generation, particularly when integrated with renewable energy sources such as solar and wind power due to its rapid response to electrical input fluctuation. Finally, the challenges and future directions of water electrolysis in hydrogen production are highlighted, including an exploration of economic and environmental considerations at large scale, offering insights into the path forward for advancing this technology sustainably. • A comprehensive bibliometric analysis of water electrolysis for hydrogen production. • Publication trends, journal rankings, and citation analysis are highlighted. • China is identified as the leading contributor in water electrolysis publications. • International Journal of Hydrogen Energy: the highest-ranked journal in this field. • Specific electrolysis methods, including AWE, PEM, and SOE are examined. [ABSTRACT FROM AUTHOR]

The paper presents an investigation of the performance of the proton exchange membrane (PEM) electrolyser directly connected with large-scale PV systems under faulty, degradation and partial shading conditions. With the direct coupled system, the power loss and external price on auxiliary devices are avoided. However, the adaptability of the direct coupled system to fluctuate solar irradiance and ambient temperature is reduced significantly compared to systems with DC-DC converters. To maximise the system efficiency, the optimal electrolyser (ELY) cell configuration is identified using an optimal sizing approach or operating strategy. This paper applied the Particle Swarm Optimisation (PSO) algorithm to find the optimal configuration for the two approaches, namely the Sizing technique and Operating strategy under different PV systems: faults, degradation and partial shading conditions. Additionally, a large-scale system is simulated to describe the characteristics of a large-scale direct coupled PV-electrolyser system with actual operating faults and phenomena. Simulations of the large-scale direct coupling system were conducted using measured irradiance and temperature data for a typical day period. Based on the collected output, it is found that compared to the optimal sizing approach, the optimal operating strategy allows the direct coupled system to increase its coupling efficiency from 0.17% to 4.47%. In contrast, the amount of hydrogen production when applying the two methods witnessed different trends, depending on the type of faults. The differences are even more significantly presented during multiple short-circuit fault scenarios. • Modelling of a large-scale direct coupling PV-electrolyser system up to 1 MW. • An analysis of typical PV system faults, partial shading, and degradation phenomenon. • A comparison of the optimal sizing approach and operating strategy. • Proposed optimal operating strategy allows 99.99% coupling factor in normal operation. [ABSTRACT FROM AUTHOR]

Clean energy devices have a great ability to change the world because they strengthen the economy and preserve society. The continuous improvement and progress in nanomaterials and nanotechnology have a great role in human life. The increasing prevalence of PEM fuel cells makes them one of the most viable sustainable energy sources. Nanostructured materials synthesis methodologies have introduced a breakthrough and found to overcome the obstacles for PEMFC commercialization. Amongst them, wet chemical approaches are rapidly expanding and beneficial for the fabrication of nanoparticles since they contribute toward the attainment of a range of essential nanoparticle characteristics like sizes, morphologies, structures, and phases. Wet chemical manufacturing enables fine-tuning of reaction parameters to generate the desired nanomaterials. This review article focuses on the latest improvements in wet chemical methods to better regulate the quality of nanomaterials. This paper examines how wet chemical approaches (hydrothermal synthesis, spray pyrolysis, sol-gel processing, and co-precipitate synthesis, among others) can contribute to the scalable manufacturing of nanoparticles to uphold rising industrial requirements. And how wet chemical methods have a significant influence on power generation systems (Fuel cells) along with their pros and cons. This review carefully analyzes and summarizes synthetic methods and optimized factors in order to prepare nanoparticles and carefully analyzes the reported data. In this paper, the electrochemical analysis, morphological evaluation, compositional analysis, and performance testing of materials produced using wet chemical techniques have been investigated. Recent signs of progress and innovative techniques used to overcome the complexities of synthetic nanoparticle processing. This article is a holistic approach including social, economic, and ecological aspects in the wet chemical process and will certainly help in the fabrication, and application of nanoparticles for PEM Fuel cells. [Display omitted] • Introduction to the status of materials synthesis in energy generating devices. • Overview of wet chemistry Approaches for PEMFC. • Impact of synthesis parameters on properties of materials. • Pros and Cons of wet chemistry techniques for material synthesis. [ABSTRACT FROM AUTHOR]

This paper explores green hydrogen-based carbon dioxide (CO 2) hydrogenation for the production of oxygenates, presenting it as a pivotal strategy for mitigating carbon emissions and advancing sustainable energy solutions. The conversion of CO 2 into oxygenates through hydrogenation emerges as a promising avenue, particularly in the context of transportation applications where the storage of hydrogen poses challenges. The substitution of fossil diesel and gasoline fuels with green hydrogen-derived dimethyl ether, or methanol/ethanol, is advantageous from a life cycle analysis (LCA) CO 2 emission perspective even without the capture of the CO 2. However, the greatest sustainability appeal is contingent on the crucial aspect of capturing CO 2 when utilizing these fuels, which is an aspect currently absent in the literature. This narrative review comprehensively explores catalytic processes, mechanisms, sustainability perspectives, and the current state of research in this evolving area. It encompasses both the production of oxygenates through CO 2 hydrogenation and the subsequent utilization of these oxygenates in fuel cells or combustion systems, emphasizing the integration of CO 2 capture technologies. The paper contributes to the discourse surrounding the environmental and technological dimensions of energy storage ecosystems, providing a holistic view of their potential to foster sustainable energy solutions. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is considered as a green and efficient way of hydrogen production. How to promote the performance of electrode and develop stable non-precious metal catalysts has caused extensive research. One of the effective strategies is combining two or more catalytic materials to build heterogeneous structures. In this paper, a series of Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 heterostructured materials were synthesized to in-situ grow Ni 3 S 2 /Ni 3 Sn 2 S 2 on Ni foam with a 3D porous structure by modulating the substance ratio of elemental cobalt and elemental sulfur through a one-step hydrothermal process. The materials have superior oxygen evolution reaction (OER) properties and urea oxidation reaction (UOR) performance. Under an alkaline electrolyte of 1 M KOH, for OER, Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 only requires overpotential of 251 mV to obtain a current density of 10 mA cm−2. In an alkaline solution of 1 M KOH +0.5 M urea, for UOR, only the potential of 1.326 V was demanded for the catalyst to reach a current density of 50 mA cm−2, but its stability over 15 h was average. Density Functional Theory (DFT) analyses suggest that Co–Ni 3 S 2 has better metallic properties and promote the dynamics in catalysis. This study put forward a new thought for future research on nickel-tin binary metal sulfide hybrid electrocatalysts with excellent freshwater, seawater and urea oxidation properties. In this paper, a series of Co x -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials was in situ grown on Ni foam by a one-step hydrothermal method, and the synthesized Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 material present excellent water and urea oxidation properties. [Display omitted] • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials were successfully synthesized by hydrothermal processes. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 electrode shows excellent catalysis in the cathode reaction of water and urea. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 requires only potential of 1.326 V to achieve a current density of 50 mA cm−2 for UOR. [ABSTRACT FROM AUTHOR]

In pursuit of energy transition objectives, Algeria is increasingly focusing on the production and utilization of low-carbon and renewable hydrogen. While hydrogen has predominantly been used in the chemical and refining industries, it holds promise for decarbonizing specific industrial sectors, enabling electricity storage, and powering the transport sector. However, several barriers must be overcome before hydrogen technologies can be widely deployed. Numerous countries, with Japan at the forefront, are heavily investing in this burgeoning market, anticipating the creation of thousands of new jobs. Hydrogen offers Algeria significant potential for greenhouse gas (GHG) reduction and substantial economic benefits. In response, the Algerian government has prioritized energy transition to new and renewable sources as part of its economic recovery plan, aiming for "green" growth through innovative and digital energy technologies. This paper's primary objective is to provide a techno-economic foundation for guiding public policy development, identifying promising opportunities for green hydrogen within Algeria's energy transition context, and outlining sustainable pathways for pilot projects that promote hydrogen adoption within the Algerian society. Additionally, this paper will explore the latest advancements in hydrogen research, technology, and applications relevant to the Algeria's energy transition. The Algerian energy minister, has reaffirmed his desire to "invest in hydrogen", an energy source presented as one of the solutions to the climate crisis. In October 2021, Algeria launched a hydrogen plan worth several billion dinars, including 100 million for research, to enable the country to develop "green" hydrogen, i.e. produced without fossil fuels. • Algeria's energy transition mission focuses on promoting energy transition, innovation, and efficiency. • The Algerian Strategy on Green Hydrogen 2050 intends to establish a supportive framework for hydrogen sector development. • Algeria has set ambitious targets: reducing its GHG emissions by 2030 and lowering its consumption of petroleum products. • Algeria export between 30 and 40 TWh by 2040 of gaseous green hydrogen, liquefied, and derived. [ABSTRACT FROM AUTHOR]

In order to meet the hydrogen refueling demand of fuel cell vehicles and reduce the cost of HRS operation process, it is necessary to study the hydrogen refueling process of cascade hydrogen storage system of hydrogen refueling station. In this paper, a thermodynamic model of the hydrogen refueling process for fuel cell vehicles is established, and the effect of the variation of these thermodynamic parameters on the specific energy consumption and utilization rate of the hydrogen refueling process is investigated in terms of the pressure ratio and capacity of the hydrogen storage tank, which is the core of the hydrogen refueling station, consisting of multiple hydrogen storage tanks. The results show that the specific energy consumption and hydrogen utilization of the hydrogen refueling station decreases as the ratio of the nominal pressure of the medium-pressure stage to the nominal pressure of the high-pressure stage increases over the course of the pressure ratio change. In addition, the capacity variation is only slightly changed as a result of the pressure ratio variation. Therefore, the lowest ratio of specific energy consumption can be found by fixing the utilization rate and by changing the pressure ratio. For example, in this paper, if the total mass of hydrogen in the station is 600 kg and the hydrogen utilization rate is required to be not less than 12 %, the optimal pressures for each level are 50.2 MPa, 65 MPa and 86.7 MPa. • A thermodynamic model of the hydrogen filling process for fuel cell vehicles is established. • The pressure ratio and capacity of cascade hydrogen storage systems were analyzed. • Specific energy consumption and hydrogen utilization are used as evaluation indicators. • The optimal pressures for each level are 50.2 MPa, 65 MPa and 86.7 MPa. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of subcooling degree and exhaust pressure on the performance of a high-pressure piston pump for pressurizing cryogenic liquid. We fabricate a lab-scale cryogenic liquid pump, conduct experiments with liquid nitrogen, and observe the significant effect of subcooling changes on the pump performance. The lab-scale pump achieves up to 30 bar of exhaust pressure and up to 45.4 g exhaust mass per cycle. This paper introduces the concept of duty cycle for the exhaust mass as a measure of pump performance. The results show that as the subcooling degree and the exhaust pressure increase, the duty cycle and the exhaust mass also increase, improving the pump performance. However, the increase in performance does not happen proportionally, and an optimal subcooling degree must be selected. This paper establishes a generalized computational model to predict the pump performance, achieving the mean absolute errors of 1.8 bar and 0.3 g/s in pressure and mass flow rate, respectively. The model can predict the exhaust mass during one stroke cycle of the pump with an approximation error of 10 %. In addition, the model predicts that pressurizing liquid hydrogen to 900 bar requires subcooling degree and its duty cycle cannot reach 100 % by reduction of specific volume. The findings suggest that subcooling can be used to enhance cryogenic liquid pump performance, and the optimal subcooling degree can be determined during the design of piston pumps to achieve high pressure. [Display omitted] • A piston-type tension-assisted cryogenic liquid pump was developed. • We identified the performance indicator of the pump as duty cycle. • This paper investigated the effect of the parameters on the duty cycle. • Subcooling degree effect on liquid hydrogen is predicted. [ABSTRACT FROM AUTHOR]

Unitized regenerative proton exchange membrane fuel cell (URPEMFC) as a self-sufficient hydrogen energy system offers a unique proposition for achieving a net zero emissions future. The system combines the operation of water. Due to the design parameters and operating conditions of URPEMFC, the potential cycling from the mode switching, high temperature, humidified environment and the long exposure of metallic components to hydrogen are the primary factors causing degradation to the system. Consequently, the conventional graphite bipolar plate (BP) suffers heavily under such an environment while giving rise to alternative metallic base materials, such as titanium, stainless steel, and aluminum. Various surface treatment and coating methods are currently under investigation to provide the required corrosion resistance while maintaining feasible manufacturing process and cost. This paper presents an overview into the degradation phenomena of URPEMFC that contributes to the corrosion of BP that is affecting the performance and future commercialization of the system. The operating condition of the system is summarized in terms of fuel cells and water electrolyzers respectively, along with the integration of both operations as a system. Next, the paper outlines the degradation phenomena observed on BP and the behavior of various materials under such conditions. The performances of various base and coating materials have been compiled as have characterization methods that are useful in measuring corrosion resistance. This paper aims to provide a better understanding on the overall degradation of BP in URPEMFC and overview of various material choices to identify the optimal corrosion mitigation solution. [Display omitted] • Breakdown of the URPEMFC operating parameters from the respective operation modes. • System design approaches allowing integration of fuel cell and electrolyzer modes. • Identification of the main degradation mechanism on the BP. • Tabulated data of various base materials and coatings performance. • Discussion of current experimental and modeling methods for corrosion resistance characterization. [ABSTRACT FROM AUTHOR]

This paper proposes a novel energy management strategy satisfying real-time and highly efficient energy management strategies for fuel cell hybrid electric vehicles (FCHEVs). The strategy is based on model predictive control (MPC), which integrates long short-term memory (LSTM) and dynamic programming (DP). A high-precision powertrain model of the investigated FCHEV is established for subsequent simulations. After training under several typical working conditions, LSTM is designed to forecast future power demands of the entire vehicle. Using the prediction results, the DP algorithm calculates the control scheme based on model predictive control. Considering the economy and durability of power sources, the results of four different control strategies are compared: thermostat, power following, traditional DP, and MPC. The MPC proposed in this paper reduces the total usage cost per 100 km on the test set by 9%, 33.5%, and −4.6%. • The economy and durability of vehicular fuel cell system are both considered. • The LSTM neural network is imported into MPC theory for vehicular power prediction. • The key parameters of MPC and LSTM are determined by referring to the greedy algorithm. • The computational load in MPC optimisation is reduced by simplifying DP algorithm. • The real-time performance of the supposed EMS on-board is validated. [ABSTRACT FROM AUTHOR]

This paper precisely estimates the looming demand for hydrogen within the transportation sector, spanning 14 pivotal G20 nations from 2022 to 2050, anchored in the global vehicle hydrogen market penetration rate. Employing a robust techno-economic modeling methodology and leveraging Geographic Information System (GIS) for enriched visualization, it unveils distinct environmental dividends across three thoughtfully devised scenarios: Business- as -Usual, Moderate, and Aggressive. Findings herald India and China as pinnacles of hydrogen demand, with South Korea and Japan tailing closely. The study forecasts the energy consumption for solar hydrogen production in G20 countries to oscillate between 3.02 and 2.89 million GWh in 2022, while production costs are anticipated to range from $8.47/kg to $10.01/kg. In an assertive scenario, the paper illuminates a pathway towards achieving a significant CO 2 reduction, unmasking environmental savings of up to a staggering 48%, equivalent to 1.5 million mtCO 2 , by 2050. [Display omitted] • Hydrogen demand of G20 countries is analyzed using GIS and techno-economic models. • The projected adoption rates of hydrogen vary among the G20 countries. • Solar energy is crucial in determining each region's annual energy demand. • China, US, and India have the highest solar potential throughout the year. • The environmental analysis shows 850–1.5 million mtCO2 total emissions by 2050. [ABSTRACT FROM AUTHOR]

The fuel cells need the high step-up DC/DC converter with low current ripples to interface to the high voltage DC grid. A novel zero voltage switching high step-up multiphase interleaved boost converter (ZVS HSMIBC) is proposed in this paper. This new converter employs advantages of low input current ripples, high voltage step-up ratio, soft-switching operation, and low switching harmonics and noise. In this paper, the two-phase interleaved structure of the proposed ZVS HSMIBC is analyzed and researched in detail as a representative topology. The relevant conclusions also can apply to multiphase (3 and above) interleaved structure of the HSMIBC. Finally, an experimental prototype is built and test, the experimental results show that the proposed converter can operated under ZVS conditions with low input current ripples and low switching noise and harmonics. In addition, this converter can obtain high voltage step-up ratio up to 45 (mn = 8, d = 0.8) with high efficiency, and proportion of the experimental ratios to theoretical ratios is also high (not less than 0.8). • A high step-up multiphase interleaved boost converter is proposed for the fuel cell power system. • The converter includes soft-switching circuit, high voltage ratio circuit, and interleaved structure. • The converter employs advantages of low input current ripples, high voltage gain, and low switching harmonics. • The operating principle and performance of the converter is verified by an experimental prototype. [ABSTRACT FROM AUTHOR]

Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. [Display omitted] Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. • Stability of ZrXH 3 (X = Zn, Cd) hydride perovskites is confirmed by Enthalpy of formation. • ZrXH 3 (X = Zn, Cd) hydride perovskites have high value of decomposition temperature. • The gravimetric hydrogen storage capacities comes out to be 1.89 % and 1.46 % respectively. • Metallic behavior is reveled by electronic structure of these hydrides. [ABSTRACT FROM AUTHOR]

Guaranteeing rapid management of oxygen excess ratio (OER) for proton exchange membrane fuel cells (PEMFC) under load variations is a challenge with practical significance. To improve the controller response of PEMFC air supply system, a fixed time fault-tolerant control strategy is proposed in this paper. A fixed convergence time of PEMFC air supply control system is quantified and guaranteed by the proposed method and the control response can be accelerated by reducing the setting time. The contributions of this paper is fourfold. Firstly, the manifold leakage fault is estimated by fixed time fault observer, which can improve the real-time fault tracking performance of the control system. Secondly, a hierarchical fixed time sliding mode controller is proposed to regulate the OER rapidly. Furthermore, a novel adaptive term is employed to reduce the effects of the chattering from fault observer in the outer loop. Finally, the effectiveness of the proposed method is verified on a real-time PEMFC simulation platform. Experimental results on a Hardware-in-the-loop (HIL) platform show that the proposed fixed time fault tolerant control strategy has the characteristics of fast response and high robustness. [Display omitted] • Fixed time fault observer is employed to monitor the manifold leakage. • Fixed time control framework guarantees a quantified stabilization time of OER. • An adaptive term reduces the chattering effects of the fault observer. • The FTC method is validated on a high-fidelity HIL platform. [ABSTRACT FROM AUTHOR]

Previous studies have found that in ceramic fuel cells using Ni 0·8 Co 0·15 Al 0·05 LiO 2 (NCAL) as the electrode, lithium compounds such as LiOH generated by reduction of NCAL anode by H 2 diffuse into oxide electrolyte membranes such as Gd 0.1 Ce 0·9 O 2 (GDC), and the "GDC-lithium compounds" composite electrolyte formed online is an excellent proton conductor. In this paper, the low-temperature electrolysis performance of proton conductor type solid oxide electrolysis cell (P-SOEC) with GDC as electrolyte and NCAL as electrode for direct electrochemical conversion of H 2 O into H 2 was investigated. It is found that at operation temperature of 550 °C, the current density of the SOEC prepared in this paper can reach 2.263 A cm−2 at 1.6 V. The composite electrolyte in the electrolysis cell reaches an ionic conductivity of 0.572 S cm−1 in the SOEC mode. The excellent hydrogen production performance proves that this new type of electrolysis cell with lithium compounds as electrodes is a promising and potential proton conductive low-temperature SOEC. • SOEC with NCAL electrodes was fabricated. • Proton conductivity of the composite electrolyte reaches 0.572 S cm−1 at 550 °C. • The electrolytic current density of the SOEC reaches 2.263 A·cm−2 at 1.6 V. • Provided a new type of SOEC and related electrolytic cell material. [ABSTRACT FROM AUTHOR]

Due to the extra evaporation loss caused by the ortho-para hydrogen conversion (OPHC) during the storage and transportation of liquid hydrogen (LH 2), the initial concentration of ortho-hydrogen (o-H 2) plays an important role in the large-scale safe operation and utilization of LH 2. However, there are very limited studies focusing on clarifying the impact of the OPHC on thermal behaviors of LH 2 tanks. In light of this, this paper establishes and develops an extended thermal multi-zone model that couples the OPHC process with the mass and energy conservation equations of the ullage and liquid for an LH 2 tank. With the help of the model, a thermodynamic analysis of the pressurization rate is performed to obtain the dominant parameter that evaluates the effect of the initial o-H 2 concentration on the pressure build-up process. The results indicate that the interfacial mass transfer rate caused by the OPHC is the dominant parameter accounting for more than 90% of the effect of all parameters on the pressurization rate during a 10-day process with an initial liquid fill ratio of 90% and a heat leakage of 40 W. Additionally, the effect of the initial o-H 2 concentration on the optimal liquid fill ratio is discussed in this paper. The results indicate that when the initial o-H 2 concentration changes from 0.2% to 10%, the optimal liquid fill ratio decreases from 82.5% to 74%. The present work provides theoretical support and guidance for controlling the o-H 2 concentration to realize the long-term and high-efficiency storage of LH 2. • Modeling of transient ortho-para hydrogen conversion (OPHC) for LH 2 tanks. • Thermodynamic analysis coupled with OPHC on LH 2 storage is conducted. • Interfacial mass transfer by OPHC determines the pressure rise in LH 2 tanks. • Initial concentration of o-H 2 reduces the optimized liquid fill ratio of tanks. [ABSTRACT FROM AUTHOR]

Due to its excellent combustion properties and environmental performance, the development of hydrogen energy has become an international trend in recent years. However, hydrogen refueling stations, which are the infrastructure for hydrogen energy development, contain flammable gases such as hydrogen and methanol, which are highly susceptible to explosion and may threaten people's health and property safety. In this paper, a dynamic risk assessment method based on Dynamic Bayesian Network (DBN) is established for combustible gas leakage accidents in hydrogen refueling stations, and the methanol to hydrogen refueling stations and liquid hydrogen refueling stations are taken as research objects to quantitatively analyze their leakage risks and accident consequences. It is found that the leakage accident probability and consequences of methanol to hydrogen refueling stations show periodicity with a period of three months, while there is no periodicity for liquid hydrogen refueling stations. The probabilities of leakage accident and serious consequences in methanol to hydrogen refueling stations show a sudden increase within a cycle, on the other hand, those in liquid hydrogen refueling stations tend to increase linearly over three years with time. In addition, based on the diagnostic reasoning function of DBN, this paper identifies the two most critical hazard sources for flammable gas leakage accident in hydrogen refueling stations: human factors and corrosion factors, and provides guidance for relevant enterprises to reduce the risk. [Display omitted] • The DBN-based leakage risk assessment in two hydrogen refueling stations was finished. • The dynamic flammable gas leakage consequences in hydrogen refueling stations were achieved. • The key factors of gas leakage in hydrogen refueling stations were determined. • The commonalities and differences between two hydrogen refueling stations were compared. [ABSTRACT FROM AUTHOR]

It reviews the papers reporting on the use of rhodium nanocatalysts in hydrogen generation from the hydrolysis of ammonia borane in the following groups: (i) water soluble rhodium complexes, (ii) colloidal nanoparticles of rhodium, (iii) rhodium(0) nanoparticles supported on carbonaceous materials such as activated carbon, graphene, carbon nanotubes, (iv) the use of oxide supports for rhodium(0) nanoparticles, (v) the use of magnetic powders as support for rhodium(0) nanoparticles to make them magnetically recoverable. In each group, the reported results are evaluated by considering the increase in the catalytic activity (specifically measured in turnover frequency), the stability and durability, the lifetime (that is, how long the nanocatalyst can be used in releasing hydrogen gas from the hydrolysis of ammonia borane at appreciable rate), reusability (that is, how many times the catalyst can be isolated and reused for the same hydrolysis reaction generating hydrogen at acceptable rate). Overall, the work reported in each of the papers is evaluated in terms of contribution to the catalytic efficiency of rhodium nanocatalysts in hydrogen generation from the hydrolysis of ammonia borane at room temperature. At the end, conclusions and suggestions are given how to increase the overall catalytic efficacy of the precious rhodium nanocatalysts in hydrolytic dehydrogenation of ammonia borane. [Display omitted] • Using colloidal nanoparticles is an efficient way of increasing catalytic activity of rhodium catalysts. • Supporting the rhodium nanoparticles on materials with large surface area increases their stability. • Selecting a suitable oxide support can increase the catalytic efficiency of rhodium nanocatalysts. • Reusability of rhodium nanoparticles can be increased by using magnetic support. [ABSTRACT FROM AUTHOR]

Hu et al. reported the hydrogen storage properties of Sc 2 C and Ti 2 C based MXene phases utilizing density functional theory (DFT) as implemented in the CASTEP code [1, 2]. Based on such calculations, the authors suggest that the MXenes should be a new family of potential hydrogen storage media. Their results claim a maximum hydrogen storage capacity of 9.0 wt% with an average binding energy of 0.164 eV/H 2 in Sc 2 C MXene indicating Kubas-type interaction between H 2 and the MXene. These investigations are of prime importance since they provide insight about further applications of MXenes for hydrogen storage. In these calculations they have used local density approximation (LDA) to estimate the adsorption energies. However, binding energies for H 2 with the MXene phases mentioned above obtained from more accurate calculations based on Generalised Gradient Approximation (GGA) and calculation including dispersion correction (GGA + vdW) show very weak binding energy (∼ 0.064 e V / H 2 ) suggesting weak physical interactions between H 2 and the MXene phases. Our accurate DFT calculations predict that these MXene phases are not suitable for hydrogen storage at realistic conditions. So we conclude that appropriate exchange-correlation functional should be used to extract hydrogen adsorption energies in nano-phases to describe their hydrogen storage properties reliably. [ABSTRACT FROM AUTHOR]

This paper reports a novel synthesis route to prepare an integrated gas diffusion electrode (I-GDE) consisting of self-supported N-doped nanonet by pyrolyzing polyaniline on carbon paper via the electrodeposition of aniline. Electrochemical experiments suggest that the integrated structure apparently improves the mass transport, electrical conductivity in the oxygen reduction reaction performance. The peak current density of the I-GDE achieves 0.71 mA cm −2 , which is almost two times to the conventional ink-based electrode fabricated with the same material under the same conditions. [ABSTRACT FROM AUTHOR]

a low-cost electrode with lawn-like NiS 2 nanowire arrays on flexible carbon fiber paper was synthesized, for the first time, via sulfurization of Ni 2 (CO 3 )(OH) 2 precursor. And the performance of this electrode as a bifunctional electrocatalyst toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) was evaluated. It shows that NiS 2 NWs/CFP requires small overpotentials of 165 mV for HER and 246 mV for OER, respectively, to deliver the current density of 10 mA cm −2 in 1.0 M KOH. The corresponding symmetric two-electrode alkaline water electrolyzer only needs a cell voltage of 1.59 V to afford 10 mA cm −2 water-splitting current density. [ABSTRACT FROM AUTHOR]

Sulfonated poly(ether ether ketone) (SPEEK) membranes have been deposited on the both sides of a sulfonic acid functionalized graphene oxide (SGO) paper to form a proton exchange membrane (PEM) with a sandwiched structure. The obtained SPEEK/SGO/SPEEK membrane could exhibit proton conductivity close to Nafion ® 112 and lower methanol permeability. The use of this SPEEK/SGO/SPEEK membrane greatly improves the performance of the semi-passive direct methanol fuel cell (DMFC). The semi-passive DMFC with the SPEEK/SGO/SPEEK membrane is found to be capable of delivering the peak power density 60% higher than that with the commercial Nafion ® 112. This, along with its comparable durability to Nafion ® 112, strongly suggests the great promise of using the SPEEK/SGO/SPEEK membrane as the PEM. [ABSTRACT FROM AUTHOR]

Foreign cations are shown to cause mass transport losses, in particular due to wettability changes in the micro-porous layers (MPL) and the carbon paper substrate, and have a major impact on the durability and the performance of polymer electrolyte fuel cells. We studied the effects of cationic impurities on fuel cell system performance, especially on the water management by employing in-situ and ex-situ contamination methods. Changes in the wettability of the carbon paper surface following the in-situ contamination injection were quantified using the Wilhelmy plate method. The CaSO 4 precipitation on the macro-pores of the carbon paper substrate after the contamination injection causes a higher wettability leading to increased flooding of the carbon paper substrate and consequent mass transport losses. An ex-situ cleaning with an acid solution is shown to be very effective in removing the salt deposits of the carbon paper substrate. During the mitigation, the highly hydrophobic MPL acts as a barrier to the transport of the recovery solution into the membrane-electrode assembly (MEA), therefore isopropanol (IPA) was added to both the contaminant solution and the recovery solution to increase the wettability of the MPL. Wetting force measurements confirm that the added IPA can alter the wettability of the MPL and can render it fully hydrophilic, enabling the transport of the recovery solution into the MEA. [ABSTRACT FROM AUTHOR]

The effects of N/C, P/C and Fe/C ratios on dark fermentative hydrogen gas production from activated carbon treated WPT hydrolysate were investigated using Box–Behnken statistical experiment design. N/C, P/C and Fe/C ratios were chosen as independent variables while the H 2 yield and SHPR were set as the objective functions. H 2 yield and SHPR functions were described by two quadratic model functions. The addition of a proper amount of N, P and Fe to the fermentation media was found to be essential to enhance the H 2 production performance. Linear and interaction terms of N/C and Fe/C did have a significant effect on the H 2 yield in the model function. However, the SHPR was significantly affected by the linear and interaction terms of N/C and P/C. The most convenient N/C, P/C and Fe/C ratios resulting maximum H 2 yield (0.656 mol H 2 /mol glucose) and SHPR (241.64 mL H 2 /g biomass.h) were determined as 0.05, 0.09 and 0.003 (w/w), respectively. [ABSTRACT FROM AUTHOR]

A paper-structured catalyst (PSC) is a flexible planar catalyst that can be stacked on the anode of SOFCs and exhibits excellent catalytic activity for the reforming of hydrocarbon fuels at the operating temperature of the SOFC. Although our final goal is the realization of direct internal reforming (DIR) SOFCs fueled by biogas by applying a PSC, the tolerance of PSCs to sulfur impurities in biogas (H 2 S) must be improved for the practical application of PSCs to DIR-SOFCs operated by biogas. In this study, an inorganic fiber network in which a layered double hydroxide (Mg/Al-hydrotalcite denoted as HT) is dispersed was prepared by a paper-making process, and Ni was then loaded in this paper matrix via an impregnation process. This Ni-loaded HT-dispersed PSC exhibited considerably higher tolerance to H 2 S than that of HT-free PSC. [ABSTRACT FROM AUTHOR]

In Lithium-air cathode, graphene containing materials have been reported as ideal cathode materials due to their large theoretical specific surface area, chemical stability, high electrical conductivity and charge capacity. In this study; three free-standing flexible graphene cathodes were produced with different thickness by vacuum filtration technique. For preparation of the graphene electrodes, graphene oxide (GO) papers were chemically reduced. Surface morphology of the produced graphene cathodes were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) was conducted to understand elemental composition of the GO paper. X-ray diffraction (XRD) technique and Raman spectroscopy were carried out to investigate the structure of the GO paper electrode. Moreover, specific surface area and porosity distribution of the GO paper was performed using Brunauer–Emmett–Teller (BET) method from N 2 adsorption and desorption isotherms and the pore size were calculated using the Barrett–Joyner–Halenda (BJH) algorithm on the desorption branch. Electrochemical performance of the free-standing graphene electrodes were assessed in ECC-Air test cell from 1.5 V to 4.5 V at a constant current density. [ABSTRACT FROM AUTHOR]

“Mass transfer in catalyst supports”and “reactive sites”are two critical factors for supported thin film catalysts. Based on such considerations, paper composed of cellulose fibers (CFs) is chosen as a competent nano-catalyst carrier because its broad porous structure is conducive to mass transfer. Then a facile aquatic synergistic synthesis is developed to decorate polypyrrole (PPy) encapsulated palladium nano-composites onto the CF paper structures. The pyrrole monomers (Py) reduce Pd 2+ to Pd nanoparticles in aqueous solution, and meanwhile the Pd 2+ initiates the polymerization of Py to PPy. In the as-prepared composite paper catalysts, the broad pores constructed by the microfibers facilitate the reactant diffusion and the Pd/PPy nanoparticles supported on the fibers provide more reactive sites for catalysis. As a result, the catalytic activity for hydrolysis of ammonia borane is improved. The H 2 turnover frequency is 21.1 mol H 2 mol Pd −1 min −1 , surpassed most other Pd based film catalysts. Importantly, excellent stability and reproducibility are also realized by the immobilization of Pd NPs by PPy layers onto fibers. [ABSTRACT FROM AUTHOR]

Here we developed a flow-based system resulting in improved performance of enzyme cascade-based biofuel cells. A paper-based biofuel cell with passive laminar flow was build to show the impact of flow on the performance of two different enzyme cascades – methanol and ethanol cascade. Both cascades demonstrated enhanced electrochemical output as a consequence of the decreased diffusion path of reaction intermediates identifying the intermediates diffusion in between enzymatic active sites as the rate limiting step in cascade operating systems. [ABSTRACT FROM AUTHOR]

Copper–Chlorine (Cu–Cl) thermochemical cycle is being explored as one of the promising technologies for large scale production of clean hydrogen from water using nuclear or renewable energy. In this method, water splitting is achieved through a series of reactions in a loop producing only hydrogen and oxygen with complete recycle of all the intermediate copper and chlorine compounds. The first step of the cycle is the hydrolysis reaction wherein steam reacts with solid CuCl 2 to form solid Cu 2 OCl 2 (copper oxychloride) and HCl gas. The products enter the subsequent steps of the cycle and are recycled back to complete the loop. Multiple side reactions in the hydrolysis step result in reduced yield and loss of chemicals from the cycle. Efficient reactor design and optimal operating conditions of hydrolysis reactor is imperative towards achieving sustained closed loop operation and reducing the energy demand of Cu–Cl cycle. This paper presents a mathematical model for the simulation of hydrolysis reaction in a bubbling fluidized bed reactor. The one-dimensional model is developed based on modified two-phase theory of fluidization and is coupled with kinetics of multiple side reactions to investigate the effect of operating parameters and hydrodynamics on the conversion and yield of Cu 2 OCl 2. The model results are validated with experimental data in 50 mm and 100 mm semi-batch fluidized bed reactors. The developed model clearly brings out the effect of different process parameters for process optimization and scale-up of the hydrolysis reactor for efficient integration in the cycle. • Modelling and experimental validation of hydrolysis reactor. • Two-phase model with variable bed hydrodynamics. • Insights into effect of operating parameters and hydrodynamics on product yield and selectivity. [ABSTRACT FROM AUTHOR]

The hydrogen pressure typically increases to approximately 700-bar for storage in high-pressure tanks. Some industry applications use such a high-pressure hydrogen but some others need lower-pressure hydrogen where the pressure is reduced through pressure reduction valves. Some energy is lost during pressure reduction which would be significant in large-scale systems. A multi-level hydrogen storage can address this issue, where the hydrogen is stored at various pressures. This paper addresses an electricity-hydrogen nexus system integrated with multi-level hydrogen storage and solar PV sites. The designed system supplies electric and fuelcell vehicles at 3 different charging points including an electric vehicle charging station, fuelcell car refueling station, and fuelcell truck refueling station. The hydrogen is stored at 30, 350, and 700-bar pressure levels and each level feeds various users. The water electrolysis is employed to generate hydrogen at 30-bar pressure and 2 compressors increase the pressure to 350 and 700-bar. The cost function, defined as the daily energy cost, is optimized at $1045.65 per day. The water electrolyzer produces the most hydrogen during nighttime when electricity is inexpensive. Under normal operating conditions, the fuel cell is not utilized due to its low efficiency of about 60%. However, it serves as a backup resource in the event of a system outage, such as when the external grid fails, in hours 22 to 24. During this time, the fuel cell is activated and produces 154 kWh. • Multi-Level Hydrogen Storage. • Electricity-Hydrogen Nexus System Integration. • Optimized Hydrogen Production and Pressure Management. • Cost Optimization and Efficiency. • Backup Resource Utilization. [ABSTRACT FROM AUTHOR]