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Abstract Electrocatalysis has received a great deal of interest in recent decades as a possible energy‐conversion technology involving a variety of chemical processes. External magnetic field application is a powerful method for improving electrocatalytic performance that is customizable and compatible with existing electrocatalytic devices. In addition, magnetic fields can assist in catalyst synthesis and act on the catalytic reaction process. This paper systematically reviews the most recent developments in magnetic field‐assisted electrocatalytic enhancement technology. The enhancement of electrocatalysis by a magnetic field is mainly represented in the three features listed below: The spin selectivity effect improves the activity of the catalyst in a magnetic field; furthermore, magnetic fields can improve mass transport and electron transport in catalytic processes (due to Lorentz forces, Kelvin forces, magnetohydrodynamic [MHD], and micro‐MHD); the magnetothermal effect may raise the reaction temperature and boost electrocatalytic activity. This review focuses on the rational design of catalytic systems incorporating the interaction between catalysts and magnetic fields, aiming to produce enhanced catalytic effects. The recommendations for further utilization of strategies for electrocatalysis and broader energy technologies for magnetic fields, as well as potential challenges for future research, are also discussed.

Green hydrogen (H2) produced by renewable energy powered alkaline water electrolysis is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions. However, efficient and economic H2 production by alkaline water electrolysis is hindered by the sluggish hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Therefore, it is imperative to design and fabricate high-active and low-cost non-precious metal catalysts to improve the HER and OER performance, which affects the energy efficiency of alkaline water electrolysis. Ni3S2 with the heazlewoodite structure is a potential electrocatalyst with near-metal conductivity due to the Ni–Ni metal network. Here, the review comprehensively presents the recent progress of Ni3S2-based electrocatalysts for alkaline water electrocatalysis. Herein, the HER and OER mechanisms, performance evaluation criteria, preparation methods, and strategies for performance improvement of Ni3S2-based electrocatalysts are discussed. The challenges and perspectives are also analyzed.

Abstract Future renewable energy supply and a cleaner Earth greatly depend on various crucial catalytic reactions for the society. Atomically dispersed metal site electrocatalysts (ADMSEs) have attracted tremendous research interest and are considered as the next‐generation promising oxygen reduction reaction (ORR) electrocatalysts due to the maximum atom utilization efficiency, tailorable catalytic sites, and tunable electronic structures. Despite great efforts have been devoted to the development of ADMSEs, the systematic summary for design principles of high‐efficiency ADMSEs is not sufficiently highlighted for ORR. In this review, the authors first summarize the fundamental ORR mechanisms for ADMSEs, and further discuss the intrinsic catalytic mechanism from the perspective of theoretical calculation. Then, the advanced characterization techniques to identify the active sites and effective synthesis methods to prepare catalysts for ADMSEs are also showcased. Subsequently, a special emphasis is placed on effective strategies for the rational design of the advanced ADMSEs. Finally, the present challenges to be addressed in practical application and future research directions are also proposed to overcome the relevant obstacles for developing high‐efficiency ORR electrocatalysts. This review aims to provide a deeper understanding for catalytic mechanisms and valuable design principles to obtain the advanced ADMSEs for sustainable energy conversion and storage techniques.

Great progress has been made in recent years in the development of low-temperature direct ammonia fuel cells (DAFCs), motivated by the recognition that ammonia is a carbon-free hydrogen carrier with high energy density, low production cost, and ease in liquefaction at ambient temperature. However, the sluggish kinetics of ammonia electrooxidation and especially complicated mass transport in the anode catalyst layer hinder the further development of DAFCs. In this work, a three-dimensional two-phase multicomponent DAFC model considering the effect of ammonia crossover has been developed. Maxwell-Stefan model, Darcy's law and Brinkman equation are utilized to simulate the multicomponent fluid motion and transport. The predicted polarization curve simulates all experimental results well. The model shows the rate of ammonia crossover decreases with the increase of current density. Besides, the effects of the physicochemical property of the anode catalyst layer, including porosity, thickness and PtIr loading, on cell performance are investigated. The modeling results indicate that decreasing porosity and increasing thickness can slightly improve the electrochemical performance of DAFCs at high current density. Meanwhile, higher PtIr loading can effectively reduce voltage loss before approaching the limiting current density.

The type IV hydrogen storage tank with a polymer liner is a promising storage solution for fuel cell electric vehicles (FCEVs). The polymer liner reduces the weight and improves the storage density of tanks. However, hydrogen commonly permeates through the liner, especially at high pressure. If there is rapid decompression, damage may occur due to the internal hydrogen concentration, as the concentration inside creates the pressure difference. Thus, a comprehensive understanding of the decompression damage is significant for the development of a suitable liner material and the commercialization of the type IV hydrogen storage tank. This study discusses the decompression damage mechanism of the polymer liner, which includes damage characterizations and evaluations, influential factors, and damage prediction. Finally, some future research directions are proposed to further investigate and optimize tanks.

Lithium metal is one of the most attractive anode materials for rechargeable batteries. However, its high reactivity with electrolytes, huge volume change, and dendrite growth upon charge or discharge lead to a low CE and the cycle instability of batteries. Due to the low surface diffusion resistance, LiF is conducive to guiding Li+ deposition rapidly and is an ideal component for the surface coating of lithium metal. In the current study, a fluorinated layer was prepared on a lithium metal anode surface by means of chemical vapor deposition (CVD). In the carbonate-based electrolyte, smooth Li deposits were observed for these LiF-coated lithium anodes after cycling, providing excellent electrochemical stability for the lithium metal anode in the liquid organic electrolyte. The CE of Li|Cu batteries increases from 83% for pristine Li to 92% for LiF-coated ones. Moreover, LiF-Li|LFP exhibits a decent rate and cycling performance. After 120 cycles, the capacity retention of 99% at 1C is obtained, and the specific capacity is maintained above 149 mAh/g. Our investigation provides a simple and low-cost method to improve the performance of rechargeable Li-metal batteries.

Abstract Next‐generation Li‐ion batteries (LIBs) with higher energy density adopt some novel anode materials, which generally have the potential to exhibit higher capacity, superior rate performance as well as better cycling durability than conventional graphite anode, while on the other hand always suffer from larger active lithium loss (ALL) in the first several cycles. During the last two decades, various pre‐lithiation strategies are developed to mitigate the initial ALL by presetting the extra Li sources to effectively improve the first Coulombic efficiency and thus achieve higher energy density as well as better cyclability. In this progress report, the origin of the huge initial ALL of the anode and its effect on the performance of full cells are first illustrated in theory. Then, various pre‐lithiation strategies to resolve these issues are summarized, classified, and compared in detail. Moreover, the research progress of pre‐lithiation strategies for the representative electrochemical systems are carefully reviewed. Finally, the current challenges and future perspectives are particularly analyzed and outlooked. This progress report aims to bring up new insights to reassess the significance of pre‐lithiation strategies and offer a guideline for the research directions tailored for different applications based on the proposed pre‐lithiation strategies summaries and comparisons.

This dataset collects the long-term dynamic durability test data and the polarization characterization test data used in our research article [1]. The dynamic durability test and the polarization characterization test of a single proton exchange membrane fuel cell (PEMFC) are all performed on the Greenlight 20 test station. The European harmonized test protocol is adapted to construct the fuel cell dynamic load test cycle (FC-DLC) used in this work. The overall durability test is composed of 3076 FC-DLC cycles, around 1008 h. To access the degradation information of the test fuel cell, the polarization characterization tests are performed periodically during the durability test. In this work, the characterizations were performed at time: 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 h. During the test period, G20 test station records all measured data, includes the dynamic load durability test dataset and the polarization test dataset. The output voltage degradation trend as well as the polarization curves are plotted and described in this work. This dataset provides the possibilities to study the degradation phenomenon of fuel cell operating by dynamic load cycles, moreover, this dataset can be directly used to various prediction models build for fuel cells.

Degradation occurs in catalyst inks because of the catalytic oxidation of the solvent. Identification of the generation process of impurities and their effects on the properties of HSC ink and LSC ink is crucial in mitigating them. In this study, gas chromatography-mass spectrometry (GC-MS) and cyclic voltammetry (CV) showed that oxidation of NPA and EA was the primary cause of impurities such as acetic acid, aldehyde, propionic acid, propanal, 1,1-dipropoxypropane, and propyl propionate. After the degassing treatment, the degradation of the HSC ink was suppressed, and the concentrations of acetic acid, propionic acid, and propyl propionate plummeted from 0.0898 wt.%, 0.00224 wt.%, and 0.00046 wt.% to 0.0025 wt.%, 0.0126 wt.%, and 0.0003 wt.%, respectively. The smaller particle size and higher zeta potential in the degassed HSC ink indicated the higher utilization of Pt, thus leading to optimized mass transfer in the catalyst layer (CL) during working conditions. The electrochemical performance test result shows that the MEA fabricated from the degassed HSC ink had a peak power density of 0.84 W cm−2, which was 0.21 W cm−2 higher than that fabricated from the normal HSC ink. However, the introduction of propionic acid in the LSC ink caused the Marangoni flux to inhibit the coffee ring effect and promote the uniform deposition of the catalyst. The RDE tests indicated that the electrode deposited from the LSC ink with propionic acid possessed a mass activity of 84.4 mA∙mgPt−1, which was higher than the 60.5 mA∙mgPt−1 of the electrode deposited from the normal LSC ink.

Graphitized black pearl (GBP) 2000 supported Pt nanoparticle catalysts is synthesized by a formic acid reduction method. The results of a half-cell accelerated degradation test (ADT) of two protocols and a single-cell ADT show that, Pt/GBP catalyst has excellent stability and durability compared with commercial Pt/C. Especially, the survival time of Pt/GBP-membrane electrode assembly (MEA) reaches 205 min, indicating that it has better reversal tolerance. After the 1003-hour durability test, the proton exchange membrane fuel cell (PEMFC) stack with Pt/GBP presents a slow voltage degradation rate of 5.19% and 36 μV h−1 at 1000 mA cm−2. The durability of the stack is improved because of the durability and stability of the catalyst. In addition, the post morphology characterizations indicate that the structure and particle size of the Pt/GBP catalyst remain unchanged during the dynamic testing protocol, implying its better stability under dynamic load cycles. Therefore, Pt/GBP is a valuable and promising catalyst for PEMFC, and considered as an alternative to classical Pt/C.

As the core component of a proton exchange fuel cell (PEMFC), a membrane electrode assembly (MEA) consists of function region (active area), structure region, and transition region. Situated between the function and structure regions, the transition region influences the reliability and durability of the MEA. The degradation of the electrolyte membrane in this region can be induced by mechanical stress and chemical aggression. Therefore, prudent design, reliable and robust structure of the transition region can greatly help avoid early failure of MEAs. This review begins with the summarization of current structural concepts of MEAs, focusing on the transition region structures. It can be seen that aiming at better repeatability and robustness, partly or total integration of the materials in the transition region is becoming a development trend. Next the degradation problem at the transition region is introduced, which can be attributed to the hygro-thermal environment, free radical aggression, air pressure shock, and seal material decomposition. Finally, the mitigation approaches for the deterioration at this region are summarized, with a principle of avoiding the exposure of the membrane at the edge of the catalyst-coated membrane (CCM). Besides, durability test methods of the transition region are included in this review, among which temperature and humidity cycling are frequently used.

In this paper, the composition, function and structure of the catalyst layer (CL) of a proton exchange membrane fuel cell (PEMFC) are summarized. The hydrogen reduction reaction (HOR) and oxygen reduction reaction (ORR) processes and their mechanisms and the main interfaces of CL (PEM|CL and CL|MPL) are described briefly. The process of mass transfer (hydrogen, oxygen and water), proton and electron transfer in MEA are described in detail, including their influencing factors. The failure mechanism of CL (Pt particles, CL crack, CL flooding, etc.) and the degradation mechanism of the main components in CL are studied. On the basis of the existing problems, a structure optimization strategy for a high-performance CL is proposed. The commonly used preparation processes of CL are introduced. Based on the classical drying theory, the drying process of a wet CL is explained. Finally, the research direction and future challenges of CL are pointed out, hoping to provide a new perspective for the design and selection of CL materials and preparation equipment.

The membrane electrode assembly was prepared by a catalyst coated membrane (CCM) with an effective active area of 10 × 10 cm2 in this work. Porous titanium plates with different diameters were used as anode collectors to study the polarization curve and electrochemical impedance spectroscopy (EIS) of the electrolyzer. The results show that the pore size of a porous titanium plate on the anode side has a significant effect on the performance of the electrolyzer. The best cell performance was obtained when the median diameter of the anode titanium plate was 12.3 um. When the current density is 1 A/cm2, the battery voltage is 2.253 V.

The construction of hydrogen refueling stations is an important part of the promotion of fuel cell vehicles. In this paper, a multi-period hydrogen refueling station location model is presented that can be applied to the planning and construction of hydrogen infrastructures. Based on the hydrogen demand of fuel cell passenger cars and commercial vehicles, the model calculates the hydrogen demand of each zone by a weighting method according to population, economic level and education level. Then, the hydrogen demand of each period is calculated using the generalized Bass diffusion model. Finally, the set covering model is improved to determine the locations of the stations. The new model is applied to the scientific planning of hydrogen refueling stations in Jiading District, Shanghai; the construction location and sequence of hydrogen refueling stations in each period are given, and the growth trend of hydrogen demand and the promoting effect of hydrogen refueling stations are analyzed. The model adopted in this model is then compared with the other two kinds of node-based hydrogen refueling station location models that have previously been proposed.

The hydrogen storage tank is a key parameter of the hydrogen storage system in hydrogen fuel cell vehicles (HFCVs), as its safety determines the commercialization of HFCVs. Compared with other types, the type IV hydrogen storage tank which consists of a polymer liner has the advantages of low cost, lightweight, and low storage energy consumption, but meanwhile, higher hydrogen permeability. A detailed review of the existing research on hydrogen permeability of the liner material of type IV hydrogen storage tanks can improve the understanding of the hydrogen permeation mechanism and provide references for following-up researchers and research on the safety of HFCVs. The process of hydrogen permeation and test methods are firstly discussed in detail. This paper then analyzes the factors that affect the process of hydrogen permeation and the barrier mechanism of the liner material and summarizes the prediction models of gas permeation. In addition to the above analysis and comments, future research on the permeability of the liner material of the type IV hydrogen storage tank is prospected.

Hydrogen production with a proton exchange membrane (PEM)electrolyzer utilized with renewable energy power is considered to be an efficient and clean green technique, but the poor oxygen evolution performance results in high energy consumption and low efficiency. In this work, a strategy is reported for the construction of a support network of the anodic catalyst layer to simultaneously ameliorate its sluggish reaction kinetics and mass transport in order to realize highly efficient hydrogen production of the PEM electrolyzer. After in situ synthesis of IrO2 nanoparticles on N–doped TiO2 nanofibers, the as–prepared IrO2/N–TiO2 electrode shows substantially enhanced Ir utilization and accelerated mass transport, consequently decreasing the corresponding cell potential of 107 mV relative to pure IrO2 at 2 A cm−2. The enhanced activity of IrO2/N–TiO2 could be due to the fact that the N–TiO2 nanofiber support can form a porous network, endowing IrO2/N–TiO2 with a large reactive contact interface and favorable mass transfer characters. The strategy in this work supplies a pathway to develop high–efficiency interfacial reaction materials for diverse applications.

It is significant to assess the hydrogen safety of fuel cell vehicles (FCVs) in parking garages with a rapidly increased number of FCVs. In the present work, a Flame Acceleration Simulator (FLACS), a computational fluid dynamics (CFD) module using finite element calculation, was utilized to predict the dispersion process of flammable hydrogen clouds, which was performed by hydrogen leakage from a fuel cell vehicle in an outdoor parking garage. The effect of leakage diameter (2 mm, 3 mm, and 4 mm) and parking configurations (vertical and parallel parking) on the formation of flammable clouds with a range of 4–75% by volume was considered. The emission was assumed to be directed downwards from a Thermally Activated Pressure Relief Device (TPRD) of a 70 MPa storage tank. The results show that the 0.7 m parking space stipulated by the current regulations is less than the safety space of fuel cell vehicles. Compared with a vertical parking configuration, it is safer to park FCVs in parallel. It was also shown that release through a large TPRD orifice should be avoided, as the proportion of the larger hydrogen concentration in the whole flammable domain is prone to more accidental severe consequences, such as overpressure.

Corrosion resistance and electrical conductivity of stainless steel bipolar plate remains a big challenge while it has been regarded as the most promising candidate for proton exchange membrane fuel cell. The purpose of this paper is to study the effects of pickling and passivation by sulfuric acid and a mixture of nitric and fluoric acids, respectively, on corrosion resistance and electrical conductivity of stainless steel 316L (SS316L) bipolar plate. First, pickling of the specimens of SS316L is performed in a 15 wt.% H2SO4. Afterwards, the specimens are passivated in a mixture of 12 wt.% HF and 4 wt.% HNO3. Electrochemical and interfacial conductivity tests are conducted to examine the change in corrosion resistance and electrical conductivity of SS316L. Finally, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) reveal the evolution of surface morphology, chemical composition and surface conductivity. The results show that the corrosion resistance and electrical conductivity of SS316L could be improved significantly by pickling and passivation. The increase in Cr:Fe ratio as well as a more uniform surface with higher conductivity is the main reason for the improvement of corrosion resistance and interfacial conductivity of SS316L.

Effects of alkaline earth metal elements and their synergistic roles with Ta for the modified Li _7 La _3 Zr _2 O _12 (LLZO) are discussed. Li _7.1 La _3 Zr _1.95 M _0.05 O _12 (M = Mg, Ca, Sr, Ba) with the substitution of alkaline earth metal ions for Zr ^4+ and Li _6.5 La _3 Zr _1.35 Ta _0.6 M _0.05 O _12 (M = Mg, Ca, Sr, Ba) with the co-substitution of alkaline earth metal ions and Ta ^5+ for Zr ^4+ are prepared. The sole substitution of alkaline earth metal elements for Zr in LLZO have little effects on improving ionic conductivity, while the modified LLZO with synergistically co-doping Ta and alkaline earth metal elements can achieve the great enhancement of ionic conductivity. The order of ionic conductivity influenced by Ta ^5+ and alkaline earth metal ions (Mg ^2+ , Ca ^2+ , Sr ^2+ , Ba ^2+ ) co-substitution for Zr ^4+ demonstrates a strong correlation with ionic radii of Mg ^2+ /Ca ^2+ /Sr ^2+ /Ba ^2+ . Particularly, the enhanced Li _6.5 La _3 Zr _1.35 Ta _0.6 Mg _0.05 O _12 with the joint substitution of Mg and Ta delivers a highest ionic conductivity of 3.45 × 10 ^−4 S cm ^−1 at room temperature.

The H2/air-fed proton exchange membrane fuel cell (PEMFC) has two major problems: cost and durability, which obstruct its pathway to commercialization. Cell reversal, which would create irreversible damage to the fuel cell and shorten its lifespan, is caused by reactant starvation, load change, low catalyst performance, and so on. This paper will summarize the causes, consequences, and mitigation strategies of cell reversal of PEMFC in detail. A description of potential change in the anode and cathode and the differences between local starvation and overall starvation are reviewed, which gives a framework for comprehending the origins of cell reversal. According to the root factor of cell starvation, i.e., fuel cells do not satisfy the requirements of electrons and protons of normal anode and cathode chemical reactions, we will introduce specific methods to mitigate or prevent fuel cell damage caused by cell reversal in the view of system management strategies and component material modifications. Based on a comprehensive understanding of cell reversal, it is beneficial to operate a fuel cell stack and extend its lifetime.

Green hydrogen (H2) produced by renewable energy powered alkaline water electrolysis is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions. However, efficient and economic H2 production by alkaline water electrolysis is hindered by the sluggish hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Therefore, it is imperative to design and fabricate high-active and low-cost non-precious metal catalysts to improve the HER and OER performance, which affects the energy efficiency of alkaline water electrolysis. Ni3S2 with the heazlewoodite structure is a potential electrocatalyst with near-metal conductivity due to the Ni-Ni metal network. Here, the review comprehensively presents the recent progress of Ni3S2-based electrocatalysts for alkaline water electrocatalysis. Herein, the HER and OER mechanisms, performance evaluation criteria, preparation methods, and strategies for performance improvement of Ni3S2-based electrocatalysts are discussed. The challenges and perspectives are also analyzed. [ABSTRACT FROM AUTHOR]