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With the advantages of simple structure, high power density, and better fuel adaptability, the hydrogen FPE is one of the ideal onboard power devices for new energy vehicles in the future. The combustion system is essential for forming the in-cylinder mixture and the stable operation of the engine. This paper compares combustion, injection, and performance at different ignition energy using high-energy ignition methods and applying computational fluid dynamics simulations. In order to further optimize the combustion system, the influence of ignition timing was discussed. The results show that with the increase of ignition energy, the flame kernel size increases continuously, the speed of flame propagation increases, and the mixture participating in combustion increases simultaneously. When the ignition energy reaches 300 mJ, the fuel combustion efficiency rises to 90.22%, and the indicated thermal efficiency rises to 32.76%. Finally, a comparison was made with a gasoline FPE; the hydrogen FPE in this paper reduces the NO emission value to less than 20 ppm without any after-treatment device, while no other pollutants are generated. The performance stability of pure hydrogen combustion under FPE is preliminarily revealed. [Display omitted] • A prototype of hydrogen FPE with a high-energy ignition system was designed. • Establish a CFD model for hydrogen FPE. • Set up the bench test and calibrate the experimental data. • Early ignition timing has the advantages of a fast heat release rate and low emission. • The performance of hydrogen FPE with different ignition energy was compared. [ABSTRACT FROM AUTHOR]

This paper investigates an intelligent strut design scheme for achieving high-performance combustion of a combustion chamber under wide-ranging flow conditions. The design process involves optimizing the base strut configuration for the design point and obtaining the Pareto front. The subsequent selection of the optimal configuration is followed by analyzing and interpreting the optimization results using single-factor analysis rules. The findings reveal that the selected optimal configuration enhances the combustion efficiency by 8.22% and reduces the force by 66.12% compared to the traditional DLR combustion chamber. Additionally, a surrogate model is constructed to investigate the influence of the rotation angle of the intelligent strut's rotating blades on the combustion efficiency and force at a Mach number range of 2–3.5. Results indicate that the intelligent strut is capable of improving combustion efficiency via regulation, and the efficiency can quickly reach a desirable level. These findings suggest that the proposed design scheme has potential applications in achieving high-performance combustion in combustion chambers exposed to wide-ranging flow conditions. • This paper investigates an intelligent strut design scheme for achieving high performance combustion. • The design process involves optimizing the base strut configuration for the design point and obtaining the Pareto front. • This design scheme aims to achieve the best comprehensive combustion. Performance based on the design point. • Results indicate that the intelligent strut is capable of improving combustion efficiency. via regulation. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) is a promising green technology to produce green hydrogen from biomass sources. SCWG uses water at supercritical conditions (temperature >374.1 °C and pressure of 22.1 MPa) as a reaction medium. The ability to process high moisture-containing biomass feedstocks has enabled the SCWG technology to process a variety of waste feedstocks from other biomass process industries to produce high value-added hydrogen gas. This review paper provides in-depth insight into the integration of SCWG with other biomass processes for processing low-value feedstocks and converting produced syngas into value-added products. These integrations provide benefits due to better utilization of biomass to produce value-added products. Also, This approach allows better optimization of the process for improved economics. A detailed discussion on the feasibility and economics of such integration has been presented in this paper. It also outlines the challenges and future outlook of the SCWG integrated process. Furthermore, it identifies the knowledge gaps with future scope to address the shortcomings of the SCWG integrated processes. • Integration of supercritical water gasification with other biorefinery processes could enhance its viability. • Upstream integrated SCWG improves biomass utilization by upgrading the waste streams of biorefineries into hydrogen. • Biofuels and chemicals are synthesized from produced hydrogen via downstream integrated SCWG processes. [ABSTRACT FROM AUTHOR]

The production of energy, food, water, and other utensils by fossil fuels generates pollution that causes constant climate change. To minimize and avoid this phenomenon, opting for less polluting energy production sources is increasingly necessary. Green hydrogen (H 2), a renewable and clean fuel, is analyzed in bibliometric terms in the present work, emphasizing photosynthetic H 2. The data were obtained through the journal database list in Web of Science, in which a total of 1507 was published between January 2010 to September 2022, dealing with the production of photosynthetic green hydrogen. The country with the most significant publication is China, with respectively 24.50% of the publications, and the Chinese Academy of Sciences has 60 co-authored papers, the largest in co-authorship—most papers published in the international journal of hydrogen energy, with 19.49% of the publications. The raw materials identified as emerging are cyanobacteria and microalgae, Rhodobacter capsulatus , synechocystis sp pcc6803 and Chlamydomonas reinhardtii pointed out as the microalgae of most significant interest. However, it is necessary to improve them, given the decrease in inactivity provided by the Calvin-Benson cycle. Life cycle assessment studies are needed, as well as H 2 storage. There is a need to reduce the levelized cost of H 2 production, which is around 9.65–25.22 USD/gallon. Studies also point to using cyanobacteria and microalgae to produce other biofuels (bioethanol biodiesel) and materials (supercapacitors, batteries, and polymers). [Display omitted] • Evaluation of the photosynthetic production of green hydrogen. • Analysis of 1507 papers from the Web of Science with CiteSpace, Vosviwer and Exell. • Advanced bibliometric analysis of future trends in the production of green hydrogen. • Using photosynthetic methods to produce biofuels. • Polymer production uses carbon dioxide and green hydrogen. [ABSTRACT FROM AUTHOR]

Noble metal single-atom catalysts (SACs) have been extensively investigated due to their unique electronic structure and high-efficiency catalytic performance. However, there are relatively few studies on the preparation of non-noble metal single atoms and their application in oxygen evolution reaction (OER). In this paper, nickel single-atom catalyst was prepared using a facile one pot method. Ni-SAC-2.5% showed uniform SACs distribution and anti-ferromagnetic property as evidenced by the aberration-corrected high resolution electron microscopy and the first-principle calculations, achieving the lowest overpotential of 220 mV (10 mA/cm2) and stable performance in 1 M KOH solution. Meanwhile, it exhibited the largest specific capacitance value of 1.77 mF/cm2 and the lowest charge transfer resistance value of 40.75 Ω due to the accelerated kinetic process. First-principle calculations further confirmed the lowest computed overpotential of 0.54 eV for Ni-SAC-2.5%. However, Ni small clusters and nanoclusters with superparamagnetic performance were observed when the Ni content was further increased to 3.5% and 4.5%, resulting in higher overpotentials of 0.85 eV and 2.01 eV for OER process as indicated by the theoretical simulation. This paper provides a facile method to prepare non-noble metal SACs and useful guidance for designing high performance OER catalysts. • Nickel single-atom catalyst was prepared using a facile one pot method. • Ni-SAC-2.5% showed uniform SACs distribution and anti-ferromagnetic property. • Ni-SAC-2.5% exhibited the lowest overpotential of 220 mV (10 mA/cm2) for OER process. • Ni-SAC-2.5% exhibited the largest specific capacitance value of 1.77 mF/cm2. • First-principle calculations confirmed the lowest overpotential of 0.54 eV for Ni-SAC-2.5%. [ABSTRACT FROM AUTHOR]

Mixing characteristics play an important role on the operational process of rotating detonation combustor (RDC). In this paper, a series of numerical calculations were conducted to analyze the influence of injection diameter, injection position, reactant mass flow rate, and equivalence ratio on mixing characteristics. Mixing performance parameters and total pressure loss in combustor dome and ignition zone were analyzed in detail. The findings indicated that all four injection conditions had significant influence on mixing characteristics, among which injection position was the most significant factor. When injection position was in convergent section, the mixing characteristics were better than those in ignition section. Reducing the fuel diameter gradually improved mixing characteristics, but also increased total pressure loss. The change of reactant mass flow rate had a minimal effect on mixing characteristics. As equivalence ratio decreased, mixing characteristics decreased and total pressure loss decreased. In addition, the comparative analysis also showed that penetration depth of hydrogen had an impact on flow field disturbance and distribution of return region, which led to the difference in mixing characteristics. When hydrogen was injected into the convergent structure section where air flow velocity did not reach sonic speed and was in acceleration phase, total pressure loss would be effectively reduced in combustor dome. • A new rotating detonation combustor model with convergent inlet structure was built. • Mixing performance parameters and total pressure loss in combustor dome and ignition zone were analyzed using RANS and LES. • Mixing characteristics of RDC were significantly enhanced when the injection position was in convergent structure section. [ABSTRACT FROM AUTHOR]

The accidental leakage of gaseous hydrogen from hydrogen refueling station facilities has the potential to result in a large fire and explosion catastrophe. The ability to forecast the spatiotemporal evolution of hydrogen plumes in real-time is crucial for monitoring the distribution of plume concentrations and mitigating the risk of fire and explosion. The utilization of deep learning has been extensively employed in a diverse range of spatiotemporal forecasting tasks. However, these approaches encounter limitations in accurately quantifying uncertainty when predicting spatiotemporal concentrations and plume boundaries. This research paper introduces a novel model called DPSTNN_H 2 Evolution, which is a deep probabilistic spatial-temporal neural network designed for forecasting the spatiotemporal evolution of hydrogen plumes. The benchmark dataset is constructed by the implementation of numerical simulations pertaining to the inadvertent leak of hydrogen within a hydrogen refueling station. The findings of the study indicate that incorporating quantified uncertainty information might enhance the precision of plume boundaries and the resilience of plume concentrations when predicting the spatiotemporal development of hydrogen. By employing Monte Carlo sampling with a sample size of m = 100 and a dropout rate of p = 0.1 , the model demonstrates the ability to provide real-time inference for 10 instances of plumes, while maintaining a high level of accuracy with R2 = 0.9829. In comparison to the current state-of-the-art model, the proposed model demonstrates superior accuracy and robustness in forecasting the spatiotemporal evolution of hydrogen plumes. In general, our proposed model has the potential to serve as a dependable option for the development of a digital twin for emergency management of hydrogen refueling stations. • Probabilistic spatial-temporal neural network model for hydrogen plume evolutions is proposed. • Normalized uncertainty contours and uncertainty intervals to improve accuracy and robustness. • Numerical experiment of hydrogen leakage and dispersion in refueling station are conducted. • Optimal hyper-parameters of the proposed model are determined • Comparison between the proposed model with point-estimation based model is conducted [ABSTRACT FROM AUTHOR]

In order to solve the problems of uneven component diffusion, weak mass transfer capability and flow field flooding in the conventional flow field of proton exchange membrane fuel cell (PEMFC), and to improve the cell output power. In this paper, a novel folded porous cathode flow field is proposed. A numerical model of three-dimensional multiphase flow is established for comparative study, which reveals the relationship between the component flow characteristics and mass transfer performance of PEMFC. The folding rib structure of the novel flow field triggers gas vortices in the channel and generates secondary flow, improves the mass transfer capability of reactants between the channel and the GDL, and alleviates the drainage problem of the porous layer under the rib. The angle, length and number of folding at the rib of the flow field were mainly changed, and the mass fraction difference coefficient (CV Mi) was used to compare the uniformity of the distribution of the components of the flow field, and the optimal flow field structure was obtained as FP6-7, which increased the current density by 44.9% compared with the traditional linear flow field. For the first time, the secondary flow evaluation criterion absolute vortex flux number J ABS n was introduced to evaluate the mass transfer performance. The influence of fluid flow characteristics on the mass transfer performance is revealed. • The folded porous (FP) flow field improves the mass transfer capacity. • The current density of PEMFC based on FP6-7 flow field was increased by 44.9%. • The mass fraction difference coefficient (CV Mi) was used to evaluate the uniformity of water-air distribution in the flow field. • The absolute vortex flux (J ABS n ) is used for the first time to evaluate the mass transfer characteristics. • The relationship between the flow characteristics of components and the mass transfer capacity in the flow field is revealed. [ABSTRACT FROM AUTHOR]

Oxygen starvation in proton exchange membrane fuel cells (PEMFCs) could lead to uneven internal current distribution, which is unfavorable to the fuel cell performance and lifetime. As oxygen starvation could occur locally, investigating the internal dynamic characteristics of PEMFC is critical to understanding the performance degradation mechanism. In this paper, the self-designed segmented cell of 396 segments is used to measure the dynamic current distributions of the automotive PEMFC with active area of 406 cm2 during oxygen starvation operation by decreasing air flow rate. As the air stoichiometry decreases from 2.4 to 0.8, the cell voltage drops gradually to 0.005 V and the internal current distribution becomes extremely nonuniform. The local current density increases to 1.64 A/cm2 at the air inlet and decreases to 0.25 A/cm2 at air outlet under the load current density of 0.6 A/cm2, which is dominated by the localized oxygen starvation around air outlet. When air flow rate is decreased to 0, the cell voltage reverses with a negative value of −0.042 V and the current distribution uniformity recovers. Under the negative cell voltage condition without air supply, the current distribution is determined by the membrane water content rather than the oxygen concentration. It is also found that larger step variation of air flow rate leads to a more significant overshoot of local current at air inlet and undershoot at air outlet. The different mechanisms for the internal current evolution of PEMFC is analyzed under Rich-Oxygen, Lack-Oxygen and No-Oxygen conditions, which are beneficial to improve air supply control strategy and the fuel cell design. • Dynamic internal performance of PEMFC under oxygen starvation is studied. • Segmented cell with 396 segments is used to measure the dynamic current distributions. • Uneven oxygen distribution worsens the uniformity of the current distribution significantly. • Under No-Oxygen condition cell voltage reverses with recovered internal current uniformity. • Step variation of air flow rate leads to overshoot and undershoot of local currents. [ABSTRACT FROM AUTHOR]

With the development of hydrogen fuel cell vehicles, hydrogen refuelling stations are required to operate at a higher pressure. However, the safety issue of high pressure hydrogen is always considered as the barrier of the wide application of such transportation infrastructures. In this paper, the safety evaluation is performed on a 70 MPa hydrogen dispenser, as one of the most vulnerable equipment to safety events in hydrogen refuelling stations. The numerical simulations are conducted for the hydrogen leakage and combustion for the prototype of the dispenser. The results show the high radiation during the combustion, and the environmental wind can reduce it by promoting the diffusion of hydrogen. Accordingly, the lethal ranges in different cases are manifested by radiation heat flux at the concerned height for the safety of humans. Furthermore, an improved design of the hydrogen dispenser is proposed to cancel the lower ventilation holes based on the analysis. As a result, the radiation heat fluxes due to the hydrogen combustion after leakage is significantly reduced and consequently lead to smaller lethal ranges, indicating the enhanced safety performance of the hydrogen dispenser. • A numerical study is conducted for the hydrogen combustion from a 70 MPa hydrogen dispenser. • The safety distance is evaluated for hydrogen leakage and combustion of dispensers under different wind conditions. • An improved design of the hydrogen dispenser is proposed and proved to be effective in enhancing the safety performance. [ABSTRACT FROM AUTHOR]

Hydrogen-enriched compressed natural gas (HCNG) technology is one of the most critical developments in the natural gas industry. To ensure the safe utilization of HCNG, the mixing effect of the two gases must be characterized and evaluated. In this paper, five types of static mixers were developed and numerically simulated. The results showed that the velocity, hydrogen blending ratio (HBR), mixer types, element aspect ratio, torsion angle, and number of elements affected the mixing effect to different degrees. Specifically, the increase in velocity and HBR improved the mixing uniformity of hydrogen and methane, but with a limited impact. Additionally, the mixing uniformity increased with the increase in the torsion angle and the number of elements, as well as the decrease in the element aspect ratio. Overall, the torsion angle had the most significant effect on mixing uniformity. Comparing the five types of static mixers, it was found that the new LPD static mixers yielded the best mixing effect, while the Y-type static mixers had the worst mixing effect. It is noted here that all the static mixers could satisfy the mixing uniformity requirements of industrial production. [Display omitted] • The influence of five models on the gas mixing effect is comprehensively analyzed. • The gas mixing effect is analyzed by three evaluation indexes. • The effects of operating conditions and spoilers on the mixing effect are studied. • The new LPD static mixer has the best effect on gas mixing. [ABSTRACT FROM AUTHOR]

The first part of the current study highlights the importance of developing a clean hydrogen supply chain (CHSC) in Iran to enhance energy security and contribute to global efforts towards sustainable energy transition. Depending on whether the focus is on domestic consumption or export of hydrogen, the study provides valuable insights into the prioritization of CHSC development pathways via multi-criteria decision-making tools (AHP, AHOP-TOPSIS, and AHP-VIKOR). The results show that for domestic hydrogen consumption (internal scenario), the best path of the supply chain includes blue hydrogen from steam methane reforming coupled with carbon capture and storage, H 2 -carriers (ammonia and methanol), natural gas grid for transportation and distribution, and industry sector as the end user. In the external scenario, however, the best path of the CHSC consists of green hydrogen production based on solar energy, and the other parts of the path include liquid hydrogen as the storage method, ship as the distribution and transportation, and industrial sector as the end user. By identifying the most suitable methods and technologies for each stage of the supply chain, this paper offers a comprehensive analysis that can guide decision-making in CHSC development. [ABSTRACT FROM AUTHOR]

There is a great desire to integrate multiple energy systems by forming low-carbon energy hubs. Among various energy platforms, the integration of power and gas networks via Power-to-Gas (PtG) technologies is introduced as a promising solution to enhance the flexibility of power grids and facilitate seamless adoption for high penetration levels of renewable energy resources. In addition, the production of green hydrogen from waste/inexpensive clean electricity has recently been identified as a potential means for large-scale energy storage, deployment of hydrogen mobility, and decarbonization of several processes that utilize hydrogen. As integrated hydrogen-based energy hubs (H 2 Hubs) attract more attention for widespread deployment, the security of such new platforms against various cyberattacks is also becoming a critical topic for investigation. This paper proposes a new data estimation technique, developed and integrated with H 2 Hubs scheduling models, for real-time optimal adaptive collection and organization of the system operating parameters for cybersecurity assessment. A new formulation is presented for the adaptive formation of a newly proposed concept, referred to as the system feasibility area , via real-time acquisition of the system operating information. The created feasibility areas are utilized for real-time post-occurrence detection of the bad scheduling data that is invisible to the existing cybersecurity layers. Numerical studies are conducted to demonstrate the efficacy and feasibility of the proposed model. The results demonstrate that the historical data can be adaptively collected in real time and successfully utilized to create feasibility areas to categorize the system operating points. • An optimal scheduling model is proposed for hydrogen-based energy hubs (H 2 Hubs). • A new data estimation method is developed and integrated with the scheduling model. • A new formulation is given for the adaptive creation of the feasibility area. • Simulation case studies are presented and discussed. [ABSTRACT FROM AUTHOR]

Hydrogen is crucial in the forthcoming low-carbon energy systems offering the potential to reduce CO 2 emissions and its versatility to be utilized across diverse energy sectors. Precise assessment of hydrogen thermo-physical characteristics is vital for the effective design and execution of numerous processes encompassing hydrogen production, transportation, storage, and utilization. In this paper, various distinct machine learning (ML) approaches, namely extreme gradient boosting (XGBoost), Random Forest (RF), Adaptive boosting (AdaBoost), and Light gradient boosting machine (LightGBM) were implemented to estimate thermo-physical properties, namely thermal conductivity, density, viscosity, and diffusivity in water based on pressure and temperature variables. For this purpose, comprehensive experimental data points covering a broad range of pressures and temperatures were acquired from the literature. The results demonstrated a strong agreement between the predictions generated by all proposed techniques and the experimental data. Furthermore, XGBoost yielded a root mean square error (RMSE) of 0.0085, 2.1548, 0.3343, and 1.5308 for the estimation of thermal conductivity, density, viscosity, and diffusivity, respectively, demonstrating superior accuracy in predicting all outcomes. In the sensitivity evaluation, it was observed that temperature, with absolute relevancy factor 0.88, 0.54, 0.246, and 0.92 had the most significant influence on the hydrogen thermo-physical properties in the order mentioned above. Furthermore, the trend analysis of the model indicated that all thermo-physical properties of hydrogen experience positive effects from temperature and pressure, except for density, which decreases as temperature increases. The leverage technique confirmed the statistical validity of both the experimental dataset used for modeling and the model's development. This study's results provide the efficient design and secure operation of hydrogen storage, refueling stations, transportation infrastructure, and production facilities. [Display omitted] • Hydrogen holds great importance in the forthcoming low-carbon energy. • XGBoost, RF, AdaBoost, and LightGBM are utilized for modeling the thermo-physical properties of hydrogen. • XGBoost demonstrates its superior accuracy in predicting thermal conductivity, density, viscosity, and diffusivity. • Temperature has the most significant influence on the hydrogen thermo-physical properties. [ABSTRACT FROM AUTHOR]

Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step thermochemical water splitting cycles, which dissociate water into hydrogen (H 2) and oxygen (O 2) via sequential thermal reduction and re-oxidation processes. Building on the thermal reduction analysis presented in Part 1, this paper zeroes in on the re-oxidation reaction within the optimal reactor framework – the counter-current reactor. It elucidates the equilibrium pathway, delineating the progression of chemical equilibrium at each incremental stage of re-oxidation. Using ceria (CeO 2) as a model redox-active metal oxide, the investigation analyzes the influence of operational parameters on the re-oxidation reaction. Findings reveal the theoretical feasibility of maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving a total extent of reduction of 0.038 and a hydrogen conversion yield of 32%. While near adiabatic operation is also achievable, practicality is constrained by a maximum total extent of reduction of 6.5·10−3. The study also explores the economic implications of thermochemical water splitting, particularly focusing on the steam-to-hydrogen output ratio. It highlights the severe economic hurdles associated with hydrogen yields below approximately 1%. Furthermore, the investigation reveals that the addition of inert gas to the re-oxidation step offers no significant advantages. Concluding the analysis, a comparative assessment exposes negligible differences in outcomes when substituting carbon dioxide (CO 2) for water (H 2 O) as the oxidant in low-temperature scenarios (800 °C). This comprehensive study not only advances the understanding of re-oxidation dynamics in thermochemical water splitting but also informs practical and economic considerations crucial for the advancement of this technology. • Reversible/equilibrium re-oxidation pathway defined for water splitting cycles. • Reversible quasi-constant temperature and quasi-adiabatic re-oxidation is feasible. • Limited impact of gas purity on re-oxidation at fixed flow/minimum temperature. • Inert gas addition offers no thermodynamic advantage in re-oxidation. • Low re-oxidation temperatures expand the solution space for high cycle efficiency. [ABSTRACT FROM AUTHOR]

The paper describes a new method for determining the energy efficiency of the life cycles of wind farms by the aggregated data of energy costs. The rationale for the use of aggregated data to determine energy costs during the life cycle of the wind farms is given. The classification of wind turbines and wind farms elements by the parameters and technical characteristics of the elements with subsequent division into groups for which aggregated data of energy costs are determined is given. Within the framework of the method have been developed an algorithm for determining energy costs on the production of elements of wind turbines and wind farms and formulas for their calculation during the life cycle of wind farms. In order to test the method, energy cost was calculated during the life cycle for two wind farms with wind turbines that differ parameters and technical characteristics of the elements and their energy efficiency was determined. It has been shown that the use of a hydrogen storage unit as part of a wind turbine makes it possible to efficiently use energy during down periods and increase the efficiency of the installation by 25–30%. It is noteworthy that a wind-hydrogen farm allows not only to accumulate excess energy during lean periods, but also to save the resource of wind turbines. When the energy reserve in the hydrogen battery reaches close to full, part of the wind turbines of the wind-hydrogen farm can be automatically temporarily stopped in a given order. This technology can provide an extension of the warranty service life for each wind turbine. [ABSTRACT FROM AUTHOR]

Mackinawite FeS is the most common corrosion product in the early stage of steel in H 2 S environment and also has an effective catalysis for hydrodesulfurization, hydrogen release reactions and heavy metal ion removal since its high specific surface area and reactive surface like other van der Waals materials. In this paper, ab initio molecular dynamics (AIMD) is used to study the interactions between small molecules (H 2 S, H 2 O and H) and FeS at 300 K. The calculation results show that the primary dissociation of H 2 S only occurs on the FeS(111) surface and H 2 S is chemically adsorbed on the (011) and (100) surfaces but physically adsorbed on the (001) surface. It will dissociate and generate H atoms when different amounts H 2 S or H 2 O molecules appear in the interlayer of FeS, in which H 2 S is more prone to dissociation. The dissociated H atoms will be "captured" by Fe/S atoms in mackinawite FeS, leading to the shrink of layer. Moreover, H atoms could combine into H 2 , which suggests that layered FeS has great potential for hydrogen generation. The diffusion coefficient of H atoms in mackinawite FeS layer is estimated about 1.67 × 10−8 m2/s. These findings have significant meaning for application of mackinawite FeS in corrosion science, hydrogen generation, hydrogen storage and other fields. • Visually show the adsorption, dissociation and diffusion of wet H 2 S on different mackinawite surface. • Clarify the effect when different molecules (H 2 S, H 2 O, H) appear in the interlayer of FeS. • Demonstrate the barrier properties of layered mackinawite to H atoms. • Give new insights into the application of mackinawite in hydrogen production and storage. [ABSTRACT FROM AUTHOR]

Due to the increase in electric energy consumption and the significant growth in the number of electric vehicles (EV) at the level of the distribution network, new networks have started using new fuels such as hydrogen to improve environmental indicators and at the same time better efficiency from the excess capacity of renewable resources. In this article, the services that can be provided by hydrogen refueling stations and charging electric vehicles in the optimal performance of microgrids have been investigated. The model proposed in this paper includes a two-stage stochastic framework for scheduling resources in microgrids, especially hydrogen refueling stations and electric vehicle charging. In this model, two main goals of cost minimization and greenhouse gas emissions are considered. In the proposed framework and in the first stage, the service range of microgrids is determined precisely according to the electrical limitations of distribution systems in emergency situations. Then, in the second stage, the problem of energy management in each microgrid will be solved centrally. In this situation, various indicators including the output energy of renewable sources, smart charging of hydrogen and electric vehicle charging stations (EV/FCV) and flexible loads (FL) are evaluated. The final mathematical model is implemented as a multivariate integer multiple linear problem (MILP) using the GUROBI solver in GAMS software. The simulation results on the modified IEEE 118-Bus network show the positive effect of the presence of flexible loads and smart charging strategies by charging stations. Also, the numerical derivation shows that the operating costs of the entire system can be reduced by 4.77% and the use of smart charging strategies can reduce greenhouse gas emissions by 49.13%. • Embedding network security constraints to ensure that each microgrid operates within safe voltage levels and avoids line capacity. • Examining the impacts of flexible loads and the charging patterns of EVs and FCVs on operational costs. • Incorporating hydrogen storage systems and refueling stations in the model to mitigate the adverse effects of renewable energy fluctuations. • Establishing a multi-objective model to consider both economic and environmental aspects of energy management in the proposed model. [ABSTRACT FROM AUTHOR]

Accurate and swift estimation of the future performance degradation of Proton Exchange Membrane Fuel Cells (PEMFCs) is crucial for the health management of PEMFC. However, most existing studies primarily concentrate on uncovering the inherent patterns of performance degradation parameters, neglecting the fundamental relationships and pattern variations between performance degradation and other characteristic parameters (such as flow rate, temperature, and pressure). This paper seeks to address this research gap. To that end, we delve into feature parameters, extracting underlying patterns of feature evolution to construct a feature exploration-based framework for predicting PEMFC performance degradation. Initially, Time-Varying Filtered Empirical Mode Decomposition (TVF-EMD) is employed to decompose each feature variable, isolating the core information of the features. Furthermore, to reduce the computational burden caused by redundant features, Uniform Manifold Approximation and Projection (UMAP) is used to perform dimensionality reduction on the decomposed feature subsequences, ensuring the efficiency and representativeness of the extracted features. Finally, to overcome the shortcomings of long short-term memory networks (LSTM) in terms of convergence and the effective use of time series information, we introduce an innovative Mogrifier LSTM (M-LSTM) model to enhance the accuracy of PEMFC performance degradation predictions. The experimental and validation results demonstrate that the extraction of feature parameters significantly enhances the predictive precision of the baseline model. Relative to the compared models, there was an improvement of at least 16.859% in Root Mean Square Error (RMSE), a minimum increase of 23.333% in Mean Absolute Error (MAE), and a boost of no less than 0.913% in the coefficient of determination (R 2 ). Simultaneously, the proposed predictive framework demonstrates good stability and accuracy in predicting PEMFC performance degradation. • Developed a novel feature processing framework for predicting the performance degradation of PEMFC. • Employed TVF-EMD in conjunction with UMAP to extract evolving trends and cyclical patterns of feature parameters. • Introduced an innovative M-LSTM network to enhance the interaction between historical information and current inputs. • Feature processing framework improves single-model performance degradation predictions [ABSTRACT FROM AUTHOR]

Current industrial use of methane depends mainly on high-temperature conversion, resulting in high energy consumption and catalyst sintering inactivation. In this paper, metal oxide catalysts with different Ni/Cr ratios were obtained by the sol-gel method for the methane activation reaction. The structure-property relationships of the catalysts were investigated by XRD, XPS, H 2 -TPR, TG, N 2 adsorption-desorption, and CV, focusing on the interaction between Ni–Cr in the composite oxide catalysts. The results showed that Ni0–NiCrO 3 /Cr 2 O 3 structure was formed after the Ni–Cr oxides underwent the reduction and calcination process, which provided a structural support for electron transfer between the two metals. The least prone to sintering nickel metal particles and the highest content of high-valent chromium ions were present in Ni 1 Cr 2. XPS confirmed that this counterpart acts as the donor and acceptor for electron transfer in the catalysts, accelerating oxidation-reduction reaction over the catalyst. The catalyst exhibited the most excellent conversion and product selectivity in the methane activation reaction. • The Ni0–NiCrO 3 /Cr 2 O 3 structured catalysts were synthesized. • Ni0 electron rich, easily gives electrons, activation of methane with NiCrO 3. • Highly valent Cr ions are electronegative, attracting electrons from Ni0. • The electron transfer between Ni and Cr accelerated the redox reaction. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO 3 RR) provides a promising method for ammonia (NH 3) producing. It is urgent to develop efficient catalysts with improved NO 3 RR performance. In this paper, Cu 3 P@Co(OH) 2 /CF heterostructure catalyst is constructed by electrodeposition of cobalt hydroxide (Co(OH) 2) nanosheet on the surface of copper phosphide (Cu 3 P) nanorod, and used as a self-supporting cathode for electrocatalytic reduction of nitrate to ammonia. The NH 3 yield reaches 0.19 mmol h−1 cm−2 at a potential of −0.17 V vs. RHE, and the faraday efficiency (FE) is 86.7 %. The study manifests that the built-in electric field generated at the p-n heterojunction interface optimizes the electron migration kinetics, and promotes the adsorption of nitrate and the convention of intermediate product NO 2 − into ammonia. As a consequence, the selectivity of NH3 is improved. The Zn-nitrate battery is assembled with the designed catalyst as the cathode, to reach a peak power density of 5.16 mW cm−2. The prepared catalyst realizes three effective functions: power output, ammonia synthesis, and nitrate pollutants treatment. [Display omitted] • Cu 3 P@Co(OH) 2 /CF heterostructure material was synthesized by low temperature phosphating and electrodeposition methods. • The built-in electric field at the p-n heterojunction promotes the convention of intermediate NO 2 − into ammonia. • Cu 3 P@Co(OH) 2 /CF effectively promotes the *H pathway for NO 3 − reduction to NH 3. • Zn-nitrate battery was built with Cu 3 P@Co(OH) 2 /CF cathode to realize multi-functional applications. [ABSTRACT FROM AUTHOR]

A safe and sustainable transition to hydrogen requires that the risks associated with hydrogen systems be rigorously investigated and quantified. Quantitative risk assessment (QRA) is a rigorous process to achieve this purpose. This paper reviews existing studies on the safety aspects of hydrogen pipelines and analyzes the applicability of existing methods and models for QRA of hydrogen transmission pipelines. This work identifies QRA research gaps for hydrogen transmission pipelines and outlines initial approaches to address them. According to our analysis, consequence modeling has received considerable attention, while limited work has been conducted to quantitatively analyze the failure causes of hydrogen pipelines. Most existing models for pipelines in general cannot be directly applied to hydrogen pipelines, yet they might serve as the basis for future hydrogen pipeline QRA models. The results provide insights into the most critical research needed to enable QRA for hydrogen pipelines. • Timely reviewed the existing studies on the safety aspects of hydrogen pipelines. • Analyzed the existing transmission pipeline systems and hydrogen's effect on them. • Analyzed existing methods and models for QRA of hydrogen transmission pipelines. • Identified research gaps in the QRAs of hydrogen transmission pipelines. [ABSTRACT FROM AUTHOR]

Excessive NO x and CO 2 emissions pose a significant challenge in the clean combustion of natural gas, which is expected to be solved through the combination of exhaust gas recirculation and hydrogen enrichment. In this study, the pollutant emission and temperature distribution of a laminar diffusion flame during the combustion of CH 4 mixed with CO 2 /N 2 /H 2 are experimentally investigated. The NO emission reduction effect of CO 2 dilution on hydrogen-enriched methane is evaluated as well. The experimental results show that CO 2 dilution has a deeper NO emission reduction and flame temperature attenuation than N 2 dilution. At a given blending ratio of 50%, CO 2 dilution effectively reduces NO emissions by approximately 50%, whereas N 2 dilution decreases NO emissions by about 10%. Compared with N 2 dilution, the peak flame temperatures of CO 2 dilution cases are reduced by 15.3 K, 45.1 K, 31.7 K, 32.6 K, and 44.3 K, respectively, when the blending ratios increase from 10% to 50% with an interval of 10%. The difference caused by the CO 2 /N 2 dilutions between the inhibition effect from the inherent attributes and the enhanced mixing effect on the flame temperature, results in a significant peak temperature gap of 45.1 K at a 20% blending ratio. H 2 enrichment enhances the flame temperature and promotes the combustion reaction process, resulting in a more compact flame structure. NO emission factors for H 2 blending ratio of 0% and 50% are 1953 mg·(kg Fuel)−1 to 2544 mg (kg Fuel)−1, respectively, which is due to the excessive NO generation because of the temperature rise in the combustion zone. CO 2 dilution demonstrates an excellent NO emission reduction effect on hydrogen-enriched methane gas. This paper may provide some references for the development and application of exhaust gas recirculation and hydrogen enrichment. • The combustion characteristics of CH 4 mixed with CO 2 /N 2 /H 2 are investigated. • CO 2 is better than N 2 in NO emissions reduction and flame temperature attenuation. • H 2 enrichment increases the NO emissions and decreases the CO emissions. • H 2 enrichment increases the flame temperature and promotes combustion reaction. • CO 2 shows an excellent NO emissions reduction for hydrogen-enriched methane. [ABSTRACT FROM AUTHOR]

Energy hubs (EHs) represent a pivotal paradigm in achieving optimal resource utilization across various energy domains. This paper presents an advanced framework for the optimal management of a smart island, leveraging the synergies within the water-electricity nexus. By integrating diverse resources, including electricity, water, heat, and hydrogen, the proposed EH model aims to meet the multifaceted demands of consumers on the island. To enhance operational efficiency, this study delves into the nuanced impacts of key EH components, elucidating their roles in meeting demand profiles and minimizing operational costs. Formulated as a mixed integer linear programming (MILP) model, the EH optimization problem is addressed using the GAMS optimization tool. The overarching objective is to fulfill consumer demand while concurrently optimizing resource utilization, considering factors such as storage degradation costs and emissions from fossil-fuel-based units. In addition to strategic optimization, this study pioneers a novel approach to stochastic parameter forecasting, integrating convolutional neural networks (CNNs) and long-short-term memory networks (LSTMs). By harnessing the capabilities of these advanced forecasting techniques, the EH model can anticipate dynamic changes in demand patterns with heightened accuracy and precision. The empirical results underscore the transformative potential of the proposed EH framework, showcasing significant reductions—up to 30%—in emission costs. Moreover, the study underscores the pivotal role of EHs as enablers for scaling up renewable energy penetration, offering a robust foundation for sustainable energy transitions in island communities and beyond. Additionally, implementing a load-shifting demand response program can lower total costs by approximately $257 per day, offering significant savings for EHs over extended periods. [Display omitted] • Modeling a mixed integer linear programming for energy management of an energy hub. • Comprehensive study on hydrogen and electric storage systems. • Uncertainty modeling using convolutional and long short-term memory networks. • Modeling water–electricity nexus to meet water and electricity demand. [ABSTRACT FROM AUTHOR]

This paper presents detailed investigations of the combustion characteristics of NH 3 /H 2 blends as a possible alternative fuel to address the pressing environmental and energy security challenges. The experimental measurements of laminar burning velocity (LBV) are reported for a range of mixture equivalence ratios (φ) varied from 0.8 to 1.2 and mixture temperatures up to 720 K using the externally heated diverging channel (EHDC) method. It is observed that LBV increases nearly four times for specific NH 3 /H 2 blends with an increase in mixture temperature from 300 K to 650 K. While predictions from various kinetic models align well at ambient conditions, discrepancies emerge at higher temperatures, emphasizing the need for refining these models to accurately predict flame propagation behaviour. A detailed sensitivity analysis of the NH 3 /H 2 /air fuel blend provides insights into critical reactions and species influencing burning velocity across different mixture conditions. Notably, reactions involving NNH radicals are found to strongly influence LBV for low hydrogen fractions in NH 3. Additionally, reaction pathway analysis (RPA) highlights dominant reactions under various conditions and reveals temperature-dependent NO emissions. The present study helps highlight the importance of understanding the combustion behaviour of NH 3 /H 2 blends for achieving carbon-free energy needs. The experimental data at elevated temperatures offers valuable insights into the combustion behaviour of these mixtures, enabling the advancements for cleaner energy solutions. [Display omitted] • LBV for X H2 = 0.3 increased fourfold from 300 K to 650 K. • Predicted LBVs aligned with low-temperature data but differed at higher temperatures. • Burning velocity rises with H 2 addition due to increased H, O, and OH species. • The significance of critical NNH radical reactions increased with H 2 addition. • Higher hydrogen fractions introduce NH + H N + H 2 resulting in Zeldovich mechanism. [ABSTRACT FROM AUTHOR]

Hydrogen energy is one of promising non-polluting and renewable energy sources. In this paper, we present a first principal study of hydrogen storage in pure C 60 fullerene cage and Stone-Wales (SW) defective C 60 cages using density functional theory (DFT) with applying both the exchange functional B3LYP and the dispersion correction wb97xd at 6–31+g(d,2p) basis set. In addition, the counterpoise correction is applied, and the basis set superposition error is calculated. The calculations underscore that the hydrogenation binding energy of C 60 cages occurs through an endothermal process for C 60 H in with a hydrogen binding energy of 0.09 eV and through an exothermal process for C 60 H out , C 60 SW 66 H out , and C 60 SW 65 H out , cages with hydrogen binding energies of −2.17 eV, −2.96 eV, and −2.20 eV, respectively. Remarkably, for the first time, the intermediate hydrogen binding energy is found inside C 60 SW 66 H in fullerene, and C 60 SW 65 H in fullerene cages with energies of −0.26 eV and −0.81 eV, respectively. The hydrogen adsorption inside the cavity of C 60 SW 66 fullerene cage is thermodynamically possible below 289.8 K and entire pressure range considered. Our results highlight, for the first time, that the endohedral cavity of C 60 SW 66 is a promising new medium for hydrogen storage due to its binding energies (−0.26 eV) and its hydrogen storage weight percentage (5.3%) that are close to the optimal conditions specified by DOE for commercial use. In addition, this study opens up a new discovery of Stone-Wales defective C 60 fullerene for further endohedral cavity applications. • New insight into endohedral cavity of Stone Wales C 60 SW 66 is reported. • For the first time, a new promising medium for hydrogen storage inside cavity of C 60 SW 66 is proved. • Binding energies of −0.26 eV and hydrogen storage weight percentage up to 5.3% are achieved inside the cavity of C 60 SW 66. • This study opens a new discovery of the SW defective C 60 fullerene for further endohedral cavity applications. [ABSTRACT FROM AUTHOR]

The growing use of hydrogen as an energy carrier in the context of a renewed energy landscape is showing very promising potential. Most notably, polymer electrolyte membrane fuel cells (PEMFCs) are at the heart of the energy revolution and provide an efficient alternative to fossil fuels. The need for accurate modeling to analyze and develop the performance of PEMFCs has prompted many researchers to make major efforts in this area. This paper proposes a new approach based on an enhanced version of the bio-inspired metaheuristic salp swarm algorithm (ESSA) to identify the unknown parameters of the PEMFC model. This innovative approach was implemented by the combination of the merits of four approaches, namely the opposition-based learning, the new category of salps, referred to as exploration salps, the crossover and mutation operators, and the survival of the fittest mechanism. The newly introduced mechanisms succeed to overcome the problem of low population diversity of the SSA algorithm, accelerate its speed of convergence, strengthen the salp exploration capabilities, and improve its convergence accuracy. The performance of this technique has been tested and validated experimentally on the voltage–current characteristic on two commercial PEMFC stacks, such as 250 W and BCS500 W. The found results are compared to those of the original SSA and six recently published competitive metaheuristic algorithms simulated in various conditions as well as nine other well-cited methods from the literature. The performance comparison involved the calculation of the sum of squared errors (SSE), Standard Deviation (STD), computational speed, and statistical measurements. In this context, the best SSE and STD values obtained for Case I range 2 were 0.60132 and 1.0597 E − 14 , while those of Case II were 0.01167 and 1.1127E−15, respectively. Based on the results, the ESSA-based approach demonstrates superior performance in determining PEMFC parameters from experimental measurements, offering enhanced stability, faster convergence speed, and greater accuracy. This method thus emerges as a highly promising avenue for PEMFC parameter estimation, providing a valuable tool for optimizing fuel cell performance and design. • Modeling and parameter extraction methods for PEMFC models are investigated. • A new ESSA is proposed to tackle the parameterization problem of PEMFC. • ESSA uses OBL, exploration salps, crossover and mutation operators, and survival of the fittest mechanism. • Experimental tests show ESSA's best accuracy, convergence speed, and stability for 250 W and BCS500 W PEMFC. • ESSA is useful to develop precise simulators, and master PEMFC design and control. [ABSTRACT FROM AUTHOR]

In this paper, by using a large eddy simulation, we study the combustion process in the HyShot II scramjet combustor. By conducting a detailed analysis of the mass-fraction distributions of the main species, such as H 2 , H 2 O and the radicals, OH and HO 2 , of the mass source terms of these main species, and of the chemical source term of the energy equation, we detect the regions where chemical reactions occur through a diffusion process and the regions where auto-ignition and premixed combustion may develop. The analysis indicates that the combustion process is mainly of diffusive type, along a thin shear layer enveloping the hydrogen plume, whereas, there could be some auto-ignition and/or premixed combustion cores inside the plume. • An innovative propulsion system for hypersonic flight was analysed. • A large eddy simulation approach was employed to study the HyShot II combustor. • A thorough analysis of both fluid dynamic and chemical aspects was performed. • More understanding of the aerothermochemistry phenomena is provided. [ABSTRACT FROM AUTHOR]

Two-step thermochemical cycle (TSTC) is a promising approach for solar-driven H 2 O splitting. However, extremely high reduction temperature (T red) is a key challenge limiting the development of TSTC. Two-step electro-thermochemical cycle (TSEC) has recently emerged to overcome this problem. However, the pros and cons of TSEC and TSTC are under debate. In this paper, a thermodynamic model was developed for studying the thermodynamic fundamentals and the variation rules of energy efficiency of TSEC and TSTC. The thermodynamic mechanisms of TSTC and TSEC were compared using the Gibbs free energy method and the Exergy & energy level analysis method. In comparison to TSTC, TSEC tends to operate at a lower T red , enabling isothermal operation at moderate temperatures (<1473 K) while sustaining a high H 2 O conversion rate. In addition, energy efficiency analysis reveals that the introduction of 0.2 V auxiliary voltage can increase the energy efficiency from 0.25 in TSTC to 0.38 in TSEC, showing the advantage of TSEC for H 2 O splitting in terms of energy efficiency. This study analyses the advantages and disadvantages of TSTC and TSEC for H 2 O splitting, demonstrating a reference for further development of solar-driven H 2 O splitting. • The thermodynamic mechanisms of TSTC and TSEC are compared. • TSEC tends to operate at a lower reduction temperature with a high H 2 O conversion rate. • A thermodynamic model is developed for studying the energy efficiency of TSEC for H 2 O splitting. • 0.2 V auxiliary voltage can increase the energy efficiency from 0.25 to 0.38. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of reversed austenite (RA) on hydrogen embrittlement (HE) behavior of a high-strength multi-alloyed steel. Three heat treated samples were fabricated by quenching-lamellarization-tempering (QLT) treatment with varying the features of RA. The experimental results revealed that the existence of reversed austenite could reduce the effective diffusion coefficient and HE susceptibility. QLT specimens exhibited the optimization of the strength and HE resistance with 6.7% filmy and stable reversed austenite, which could hinder the hydrogen diffusion, reduce local hydrogen concentration, delay the crack initiation and further arrest the crack propagation. Moreover, a 23% reduction in hydrogen embrittlement susceptibility of QLT specimens was achieved by comparing with quenching-tempering (QT)specimens. However, the interface of RA and matrix was a preferred site for crack initiation. • The role of "lamellarization" on the hydrogen embrittlement was investigated. • Both fraction and stability of revered austenite affected the HE behavior. • The interface of revered austenite and matrix is a preferred site for crack initiation. • The role of RA on the crack propagation was discussed. [ABSTRACT FROM AUTHOR]

Hydrogen ejectors effectively utilize excess unreacted hydrogen. However, traditional ejectors have limited operational ranges and are only suitable for specific power ranges. This paper presents a dual-nozzle ejector aimed at broadening its operational range through different working modes. A simulation model, validated by experiments, is employed based on the working principles of ejectors. Spiral blades are installed at drive end to improve the recirculation efficiency. Flow characteristics, including streamwise and spanwise vortices at high power, are also investigated in different modes. Results indicate that optimal operating range for Ring-nozzle(RN) mode is between 31.1 and 124.4A. When output current exceeds 124.4A, it is necessary to switch to Central-nozzle (CN) or Double-nozzles (DNs) mode. Analysis of streamlines and velocity vectors reveals that installing spiral blades can modify directions of primary flow. Blades with appropriate distortion should be selected. In CN mode, when stack reaches 60% of rated power, installing 20° spiral blades has a minimal impact on stability of radial flow. Installing 30° or 40° spiral blades is suitable for full-load condition. In DNs mode, installing 30° spiral blades enhances acceleration of gas flow with lower influence from radial influx. This ejector provides assurance for upgrade of fuel cell stacks by incorporating recirculation technology. • A dual-nozzle ejector with spiral guide blades is designed, verified and evaluated. • Installed spiral blades change direction and gather kinetic energy of primary flow. • Advantageous working conditions of different modes with blades are discussed. • Flow mechanism of different blades under high power in two modes is analyzed. • Flow acceleration and losses should be balanced by changing the twist of blades. [ABSTRACT FROM AUTHOR]

This paper presents a cryogenic turbo-electric hybrid propulsion system (TEHPS) for a 70–80 seat class turboprop regional aircraft, integrating superconducting technology with liquid hydrogen (LH 2) cooling. LH 2 is selected as the cooling medium for the designed cryogenic cooling circuit, and the evaporated hydrogen gas is channeled to a hydrogen fuel cell for electricity generation, making full use of the energy content of the hydrogen. Parametric modeling of critical components is conducted to determine mass, power and heat loss parameters under feasible operating temperature conditions. Four propulsion schemes are conceptualized based on power matching combinations of turbo-engines, hydrogen fuel cell and battery during cruise, descent and landing phases. Performance comparison and analysis of the cryogenic TEHPS for a typical mission profile in 2035 is conducted, considering three projected scenarios – conservative, baseline, and optimistic – derived from existing data. The results show that propulsion Scheme 1, combining turbo-engines, fuel cell and battery for cruise, significantly reduces aviation fuel mass and pollutants emissions, cutting fuel consumption by 34.2%–38.6% at specific power parameters and potentially doubling the cruising range. Propulsion Scheme 3, employing turbo-engines for cruise and a combination of fuel cell and battery for descent and landing, achieves the lowest total mass and highest power-to-weight (PTW). In optimistic scenarios, the PTW ratio reaches 2.40 kW/kg, with baseline and conservative scenarios at 1.81 kW/kg and 1.16 kW/kg respectively, demonstrating significant advancements in propulsion efficiency and sustainability. • Innovative design for a cryogenic turbo-electric hybrid propulsion system. • Developed a cryogenic cooling circuit for efficient hydrogen energy recovery. • Detailed dimensional modeling of critical system components. • Evaluation of performance parameters in different scenarios and propulsion schemes. [ABSTRACT FROM AUTHOR]

The proliferation of hydrogen fuel cell vehicles calls for effective planning of hydrogen supply facilities. This paper focuses on renewable energy-based distributed hydrogen supply networks (DHSNs), with on-site production and vehicle-based transport. To explore the energy synergism effect, we propose multinetwork constrained planning of hydrogen-power supplying facilities. Considering the double-layer coupling mechanism (DCM), multiple DHSN equipment planning is coordinated with the generation planning of the power distributed networks (PDN). Firstly, the DCM is proposed considering structured multi-component equipment, inter-layer hydrogen couplings, and cross-network power couplings. Secondly, to formulate the DCM, we develop a structured deployment model for DHSN equipment to enhance system integrality and non-redundancy. Specially, to release more flexibilities, inter-layer transport is modeled by proposing a spatiotemporal extended vehicle routing problem model incorporating multiple loading stations with trip coordination. Thirdly, a planning method is proposed to coordinate the planning of hydrogen-power supply facilities in coupled networks, incorporating the double-layer coupling constraints, station operation constraints, and PDN constraints. Test systems are employed to verify the effectiveness of the proposed method. • The double-layer coupling mechanism is proposed for distributed hydrogen supply network (DHSN) and power distribution network. • A structured deployment model is proposed for the DHSN equipment. • Inter-layer hydrogen transport is modeled by extended vehicle routing. • A coordinated planning method is established for the distributed generators and DHSN facilities. [ABSTRACT FROM AUTHOR]

Nanofibers have been widely used in the construction of proton exchange membranes(PEM), which can be used to modify Nafion membranes and enhance their mechanical properties. With the addition of nanofibers, some of the sulfonic acid active sites in the perfluorosulfonic acid matrix are occupied, and the conductivity decreases. A covalent organic framework (COF) can be used to compensate for this. In this paper, hybrid COFs modified with sulfonic and pyridine groups were selected and synthesized in situ on polyacrylonitrile (PAN) fibers, and the fibers were placed in a perfluorosulfonic acid matrix to form a sandwich shaped composite membrane. The hybrid COF generates a small fiber-like structure to connect the PAN fibers, which improves the connectivity between three-dimensional nanofibers. This structure also plays a role in enhancing longitudinal proton transport ability of the composite membrane, which provides a new idea in the study of PEM. • In situ synthesis of hybridized COFs of sulfonated pyridines on fibers. • COF synthesis connects fibers to each other and increases longitudinal connectivity. • The fibers are added to the perfluorosulfonic acid solution together with COF to form a sandwich structure. • The prepared composite membrane has high conductivity and performance stability. [ABSTRACT FROM AUTHOR]

By offering promising solutions to two critical issues – the integration of renewable energies into energy systems and the decarbonization of existing hydrogen applications – green hydrogen production through water electrolysis is set to play a crucial role in addressing the major challenges of the energy transition. However, the successful integration of renewable energy sources relies on gaining accurate insights into the impacts that intermittent electrical supply conditions induce on electrolyzers. Despite the rising importance of addressing intermittency issues to accelerate the widespread adoption of renewable energy sources, the state-of-the-art lacks research providing an in-depth understanding of these concerns. This paper endeavors to offer a comprehensive review of existing research, focusing on proton exchange membrane (PEM) and alkaline electrolysis technologies operating under intermittent operation. Despite growing interest over the last ten years, the review underscores the scarcity of industrial-scale databases for quantifying these impacts. [Display omitted] • Dynamic features, e.g. event frequency and amplitude, affect efficiency and durability of alkaline and PEM electrolyzers. • Intermittent operation promotes electrolyzer decay, but literature lacks consensus and studies on alkaline technology. • Industrial-scale assessments of intermittency impacts are significantly lacking for both alkaline and PEM technologies. • Developing standardized methods is crucial to understand how intermittency affects electrolyzer efficiency and durability. [ABSTRACT FROM AUTHOR]

To alleviate the energy crisis and achieve green energy conversion, the heterojunctions that can be applied to the photocatalytic decomposition of water have attracted attention. In this paper, we design a novel two-dimensional GeC/SnSe 2 heterostructure and investigate in detail the structural stability, electronic characteristics, photocatalytic activity and optical behavior as well as the effects due to the applied strain based on the first-principles. Firstly, the most stable γ-stacking mode is determined by combining energy comparison, thermodynamic and dynamic studies. Second, the analysis of electronic properties demonstrates that the GeC/SnSe 2 heterostructure exhibits a type-II energy band arrangement and a direct Z-scheme photocatalytic mechanism. This pivotal aspect enhances the separation of photogenerated carriers at the interface and facilitates the active participation of the most proficient materials in oxidation-reduction processes during photocatalytic hydrolysis reactions. The hydrolysis reaction's Gibbs free energy shift demonstrates the GeC/SnSe 2 heterostructure's superior photocatalytic activity in neutral and alkaline environments and can spontaneously carry out the overall hydrolysis reaction, and this outstanding ability is not affected by the −4% to 4% strain range. In addition, the GeC/SnSe 2 heterostructure has outstanding solar-to-hydrogen efficiency (58.18%) and excellent light absorption capability (up to 4 × 1 0 5 cm − 1 ) within visible light. The implications of these discoveries point towards the direct Z-scheme GeC/SnSe 2 heterostructure holds promise as an excellent candidate for photocatalytic water splitting applications. Free energy descriptions of the GeC/SnSe 2 heterostructure participating in water splitting (a) hydrogen evolution reaction and (b) oxygen evolution reaction under different conditions. Top and side views of the most stable adsorption sites for (c) H on the GeC layer and (d) OH, (e) O and (f) OOH on the SnSe 2 layer of the GeC/SnSe 2 heterostructure. The H and O atoms are represented by pink and red balls, respectively. [Display omitted] • The GeC/SnSe 2 heterostructure is thermodynamic, dynamic and thermal stable. • The GeC/SnSe 2 heterostructure exhibits direct Z-scheme mechanism and strong redox capacity. • Gibbs free energy diagram of water splitting demonstrates its excellent spontaneous reaction capability. • The GeC/SnSe 2 heterostructure has excellent light absorption capability within visible light. [ABSTRACT FROM AUTHOR]

Membranes on palladium alloy basis with surface modified by nanoparticles with high catalytic activity are useful in deep hydrogen purification and single-stage process of high-purity hydrogen production. This paper reports the development and improvement of methods for synthesis of Pd-based pentatwinned nanoparticles of strictly specified morphology with certain shapes, facets and composition. The competing effect of surfactants and optimization of the halide ions ratio in solution make it possible to direct a particle growth towards formation of pentatwinned Pd-nanostars. Pd–23%Ag coatings synthesized on the surface showed uniquely high peak current density of up to 238 mA cm−2 in alkaline methanol oxidation reaction. This is due to both increased surface area and greater catalytic activity of nanostars' facets. A record increase in hydrogen permeability of up to 12.5 mmol s−1 m−2 at 100 °C has been achieved for palladium-silver membranes with modified surface. This indicates an acceleration of sorption/desorption stages. The developed method for controlling morphology of nanoscale coatings opens the way to the production of membrane hydrogen filters, which operate at room temperature. [Display omitted] • Surface-modified Pd membranes are an excellent tool for high-purity hydrogen production. • Approaches have been developed to manipulate the processes of morphology fine-tuning of Pd nanostars. • Modified Pd–Ag films exhibited high peak current density up to 238 mA cm−2 in methanol electrooxidation. • A record flux density up to 12.5 mmol s−1m−2 at 100 °C has been demonstrated in membrane hydrogen purification process. • Modified membranes open up the possibility of deep hydrogen purification at low temperatures. [ABSTRACT FROM AUTHOR]

Magnesium-based materials are favored by researchers because of their high hydrogen storage capacity, but they cannot be put to daily use because of their more demanding reaction conditions. Recently, the method to improve the hydrogen storage performance of MgH 2 by catalyst doping has been widely investigated. In this paper, Co 3 O 4 catalysts were prepared by homogeneous precipitation method. It was demonstrated that the Co 3 O 4 catalyst could effectively improve the hydrogen storage performance of MgH 2. According to the experimental results, the dehydrogenation onset temperature of the MgH 2 +15 wt% Co 3 O 4 composite was about 200 °C, which was about 130 °C lower than that of pure MgH 2 , and the amount of dehydrogenation was 6.26 wt%. The dehydrogenation activation energy of the MgH 2 +15 wt% Co 3 O 4 composite was reduced to 89.13 kJ/mol, which was about 45.7% lower than that of pure MgH 2. After complete dehydrogenation, the composites started to absorb hydrogen at 50 °C with 6.2 wt%, while the activation energy of reabsorption was also reduced to 47.97 kJ/mol. After 10 cycles of MgH 2 +15 wt% Co 3 O 4 composites, the hydrogen storage capacity of MgH 2 could still be maintained at 99%, which indicated that it had good cycling stability. It was confirmed by various characterizations that Co 3 O 4 was uniformly distributed on the MgH 2 matrix after ball milling. After the first reaction, Co 3 O 4 was converted to CoO, which was uniformly attached to the Mg/MgH 2 surface and stabilized during the cycling process, continuing to provide active sites for hydrogen. The hydrogen storage composite MgH 2 +Co 3 O 4 was prepared in this study, and Co 3 O 4 was uniformly distributed on the MgH 2 matrix. In the first hydrogen release process, Co 3 O 4 is gradually converted to CoO, and then in the hydrogen absorption process, hydrogen enters Mg. During the cycle, the CoO is in a stable state and evenly dispersed on the Mg/MgH 2 surface, continuing to provide an active site for hydrogen. [Display omitted] • Co 3 O 4 with good air adaptation performance is applied to MgH 2 system. • Composites started to release H 2 at 200 °C and could start to absorb H 2 at 50 °C. • The activation energy of de/hydrogenation was significantly reduced for composites. [ABSTRACT FROM AUTHOR]

The importance of the energy transition and the role of green hydrogen in facilitating this transition cannot be denied. Therefore, it is crucial to pay close attention to and thoroughly understand hydrogen storage, which is a critical aspect of the hydrogen supply chain. In this comprehensive review paper, we have undertaken the task of categorising and evaluating various hydrogen storage technologies across three different scales. These scales include small-scale and laboratory-based methods such as metal-based hydrides, physical adsorbents, and liquid organic hydrogen carriers. Also, we explore medium and large-scale approaches like compressed gaseous hydrogen, liquid cryogenic hydrogen, and cryocompressed hydrogen. Lastly, we delve into very large-scale options such as salt caverns, aquifers, depleted gas/oil reservoirs, abandoned mines, and hard rock caverns. We have thoroughly examined each storage technology from technical and maturity perspectives, as well as considering its techno-economic viability. It is worth noting that development has been ongoing for each storage mechanism; however, numerous technical and economic challenges persist in most areas. Particularly, the cost per kilogramme of hydrogen for most current technologies demands careful consideration. It is recommended that small-scale hydrogen storage technologies such as metal hydrides (e.g., MgH 2 , LiBH 4) need ongoing research to enhance their performance. Physical adsorbents have limited capacity except for activated carbon. Some liquid organic hydrogen carriers (LCOHs) are suitable for medium-scale storage in the near term. Ammonia-borane (AB), with its high gravimetric and volumetric properties, is a promising choice for medium-scale storage, pending effective dehydrogenation. It shows potential as a hydrogen carrier due to its high storage capacity, stability, and solubility, surpassing DOE targets for storage capabilities. Medium-scale storage, utilising compressed gas cylinders and advancements in liquefied and cryocompressed hydrogen storage, requires cost reduction measures, and a strategic supply chain. Large-scale storage options include salt caverns, aquifers, and depleted gas/oil reservoirs, with salt caverns offering pure hydrogen, need further techno-economic analysis and deployment projects to mature, but storage costs are reasonable, ranging mostly from €0.25/kg to €1.5/kg for location specific large-scale options. • Comprehensive review of hydrogen storage technologies from small to very large scale. • Metal hydride MgH 2 shown to be economically viable with storage at €2.8 per kg. • Ammonia-borane (AB) offers promising medium-scale hydrogen storage potential. • Technological advancements are enhancing compressed gas hydrogen storage systems. • Large-scale hydrogen storage costs vary between €0.25 and €1.58 per kg. [ABSTRACT FROM AUTHOR]

Online fault diagnostics is a crucial consideration for fuel cell systems, particularly in mobile applications, to limit downtime and degradation, and to increase lifetime. Guided by a critical literature review, in this paper an overview of Health management systems classified in a scheme is presented, introducing commonly utilised methods to diagnose FCs in various applications. In this novel scheme, various Health management system methods are summarised and structured to provide an overview of existing systems including their associated tools. These systems are classified into four categories mainly focused on model-based and non-model-based systems. The individual methods are critically discussed when used individually or combined aimed at further understanding their functionality and suitability in different applications. Additionally, a tool is introduced to evaluate methods from each category based on the scheme presented. This tool applies the technique of matrix evaluation utilising several key parameters to identify the most appropriate methods for a given application. Based on this evaluation, the most suitable methods for each specific application are combined to build an integrated Health management system. • HMS methods for FC diagnosis are introduced and classified into three main categories. • New scheme is introduced categorising HMS methods by approach and characteristics. • Matrix evaluation is introduced rating HMS methods for individual FC application. • Method properties affect classification results requiring evaluation for each use case. • For FCs, feature extraction, reduction and fault classification methods are chosen. [ABSTRACT FROM AUTHOR]

The design and fabrication of active and stable nanostructured electrocatalysts for hydrogen production from the electrochemical water splitting is one of the most important strategies for economical hydrogen production and replacement fossil fuels. Using of Ni-based nanostructured alloy electrodes, synthesized via electrodeposition method, due to having a high active surface area, being binder-free, and also the synergistic effect between the alloy elements, can significantly reduce the energy consumption during hydrogen production. Due to the importance of alloy electrodes and the lack of a comprehensive review in this field, in this review article, at first, the advantages and brief mechanism of the electrodeposition method for the synthesis of nanostructured electrodes are given, and then the types of alloy systems and the resulting morphologies are reviewed. Finally, recent developments in the field of alloy systems for hydrogen production are summarized. Moreover, various methods of creating different alloy nanostructures with electrodeposition method are also described in this article. The purpose of this article is to create a deep understanding of the application of alloy nanostructures and to provide a guide for the synthesis of active and stable electrodes for hydrogen production. In addition, using this review paper, one can able to select appropriate alloy system for reaching the best electrocatalytic properties. • Different modes of electrodeposition mechanisms was reviewed. • Electrodeposited metallic nanostructures have favorable electrocatalytic activity. • Various morphologies can be fabricated via electrodeposition process. • Advantages of electrodeposition process over other methods was highlighted. [ABSTRACT FROM AUTHOR]

The main advantage of Transmission Switching (TS) is decreasing the cost function in a power system. Using TS requires a high number of transmission switching in the system, which can cause some problems in the long run. These problems include decreased lifetime and failure of circuit breakers (CBs), higher repair and maintenance costs, line outage, increased probability of load shedding, and lower reliability of the system. In this paper, congestion management is utilized in the unit commitment problem constrained to the security with the TS to decrease the number of switching. This methodology will resolve the mentioned problems and improve the overall security of the system. Besides, a grid-connected water-power package is suggested to make relaxation for the line congestion which results in the alleviation of the transmission switching. The proposed water-power system is restructured regarding the fuel cell based renewable resource considering the hydrogen tank. Indeed, such a restructured system utilizes the water grid to generate the hydrogen and then power with the aim of linking the electrical grid. Also, on the account of being uncertain of some parameters coming in the electrical grid, an uncertainty-based UT function is addressed to handle uncertainty impacts on the grid's performance. To make awareness-raising, we carry out an outage of the generators as a different contingency scenario of the problem. Finally, the introduced model is testified on two 6-bus and 118-bus grids and solved by Bender's decomposition method. The simulations are performed in GAMS software to confirm the introduced approach effectiveness. Inferred from the results that the proposed strategy can help the grid operator lessen the line congestion up to an acceptable level. • Proposing a coefficient congestion-based water-power energy strategy to amend the transmission switching. • Modeling linking energy management for multi-energy demands based on the water-power energy system. • Improving the line congestion during the grid-connected mode. • Representing the UT-based uncertainty strategy to model the high-risk multi-energy demands. [ABSTRACT FROM AUTHOR]

With the future of green energy relying on increases in green-energy production scale to support demand, placing importance on location selection for new energy production methods is going to be vital to secure a zero-carbon future. In this paper, a method called H2Locate is introduced to conduct a down selection sequence for identifying hydrogen production plant location within a defined region. Following the method, resource availability, energy availability, and social impact metrics are analyzed to understand which variables are most vital and what data must be obtained to achieve confidence in the selection of an implementation location. An illustrative example using Oklahoma as the region is produced to demonstrate the proposed method. The counties within Oklahoma are analyzed to identify potential subregions for implementing a hydrogen production plant. Excel-based software, The Probability of Hydrogen Implementation (PHI), using publicly available data regarding energy, resources, and social variables is utilized to carry out the proposed method. Considering the illustrative example with a 290 MW alkaline electrolysis facility, we find that Kay County, Johnston County, Caddo County, and the counties directly surrounding them are the most suitable locations in Oklahoma for the implementation given variables related to the desired energy, resource, and social metrics. • The H2Locate down selection method guides hydrogen production plant location selection. • Analyzes 7 hydrogen hub reports to identify key hydrogen industry variables. • Categorizes energy, feedstock, and social factor variables utilized in the H2Locate method. • An illustrative 290 MW alkaline electrolysis example in Oklahoma identified Kay, Johnston, and Caddo counties as prime locations. [ABSTRACT FROM AUTHOR]

Due to the coupling of multiple physical fields inside proton exchange membrane fuel cell (PEMFC) and the complex and changeable external application scenarios, the faults of PEMFC system greatly affects its engineering application. The paper proposes an ensemble learning-based fault diagnosis method for PEMFC systems, utilizing five distinct algorithms to develop an integrated ensemble classifier for fault detection. The original sample dataset collected from fuel cells undergoes a process of deep feature extraction to obtain a composite feature sample dataset, which is then inputted into an ensemble classifier to establish a fault diagnosis model. The experimental data of four kinds of faults of 80 W fuel cell test bench, EC fuel cell system and 50 W water-cooled fuel cell test bench are analyzed by using this classification model. The results show that the accuracy and generalization of the ensemble learning algorithm for different fault diagnosis of PEMFC system in different application environments are verified. • Adopt multiple classification algorithms for fault modeling and diagnosis. • Good applicability to different faults is shown in different test scenarios. • Compared with a single algorithm, it has higher fault identification accuracy. [ABSTRACT FROM AUTHOR]

Achieving low cost at high performance is difficult for direct ammonia microfluidic fuel cell (DAMFC) as a portable clean energy conversion device. In this work, a DAMFC with Ni nanoparticles anode and catalyst-free cathode is proposed to realize low cost and high performance of the fuel cell at room temperature. Due to the uniform distribution and spherical geometry of the Ni nano-catalyst, the Ni anode prepared by cyclic voltammetry owns excellent activity of ammonia oxidation. Meanwhile, sodium persulfate having strong oxidizing properties is selected as the oxidant, resulting in catalyst-free carbon paper by cyclic voltammetry treatment directly used as the cathode to greatly reduce the cost of the DAMFC. By optimizing the electrodeposition conditions of Ni electrode and the operating conditions of fuel cell, the DAMFC achieves optimal performance. The maximum power density is 8.43 mW cm−2 and the limiting current density is 78.58 mA cm−2, which is higher than that of most previously reported low-temperature ammonia fuel cells. Moreover, the fuel cell has good stability. Therefore, it proves that a DAMFC with Ni nanoparticles anode and catalyst-free cathode is an effective method to realize low cost and high performance of the ammonia fuel cell at room temperature. [Display omitted] • A low-cost and high-performance ammonia microfluidic fuel cell is proposed. • The spherical nickel nanoparticle catalyst with uniform dispersion is prepared. • Sodium persulfate with strong oxidizing property is selected as oxidant. • The effect of reactant concentration on cell performance is discussed. • The introduction of sodium persulfate removes noble-metal catalyst and improves cell performance. [ABSTRACT FROM AUTHOR]

This paper addresses the urgent need for efficient hydrogen storage methods in the context of combating climate change and transitioning to sustainable energy sources. Among various storage options, LiBH 4 is highlighted for its high volumetric and gravimetric energy densities, critical factors in determining its suitability for energy applications. However, challenges arise due to its high thermolysis temperature, which poses difficulties, especially in applications like automotive use where high temperatures are required. The commercial viability of LiBH 4 remains a significant obstacle due to the nascent stage of chemical hydride technology and the absence of large-scale production facilities. Environmental concerns also loom large, as the production of LiBH 4 relies on extensive mining of lithium and boron, known for their environmental impact. Furthermore, the economic feasibility of LiBH 4 as a hydrogen storage medium is questioned, given the substantial portion of total expenses attributed to hydrogen costs, affecting all methods except those based on fossil fuels or electricity. Nevertheless, there is optimism that with technological advancements and improved infrastructure, the costs associated with LiBH 4 and hydrogen storage overall may decrease over time. In conclusion, while LiBH 4 presents promising energy density characteristics, its practical implementation faces challenges such as high production costs, environmental concerns, and technological limitations. Overcoming these obstacles is crucial for realizing a sustainable and carbon-free energy landscape driven by hydrogen. • LiBH 4 shows promise for high energy density storage but faces obstacles high production costs and environmental concerns. • A comprehensive decision matrix analysis showcases the strengths and weaknesses of various hydrogen storage options. • LiBH 4 may find applications in small-scale personal storage due to its safety and energy density. [ABSTRACT FROM AUTHOR]

Hydrogen is considered a truly clean energy source with great potential for replacing fossil fuels. However, the special physical and chemical properties of this source make large-scale, safe, and efficient storage challenging, thus limiting its widespread use. Consequently, an underground hydrogen storage system inspired by underground methane storage and CO 2 geological sequestration has been proposed, and it is increasingly becoming a focus of research. Depleted oil reservoirs are ideal sites for such systems. Nevertheless, research on these types of underground hydrogen storage systems is limited to a few feasibility assessments, and the hydrogen seepage laws in reservoirs with residual oil are not well understood. In this paper, a study was conducted involving mathematical modeling and numerical simulation of underground hydrogen storage, which was converted from the SSZ low-permeability depleted oil reservoir in Bohaiwan Basin, eastern China, to reveal the seepage patterns between hydrogen and complicated in situ fluids (oil, gas, and water). First, a comprehensive analysis was conducted using numerous rock samples and experimental data to identify the composition, genesis, and distribution patterns of the sandstone reservoir, detailing its internal pore structure and fluid distribution postdepletion characteristics. Then, the hydrogen seepage properties in the presence of oil films in the three main throat types of low-permeability sandstone were analyzed, and corresponding mathematical models of the different throats were established. Finally, a numerical simulation of underground hydrogen storage was conducted to assess the impacts of various parameters, such as injection speed, reservoir heterogeneity, and residual oil saturation, on hydrogen seepage. The planar and vertical diffusion patterns of hydrogen were clarified, and the key factors affecting the efficiency of underground hydrogen storage were analyzed, offering suggestions for the establishment of stable and efficient underground hydrogen storage systems. • Selection and description of typical low-permeability reservoirs for UHS. • Mathematical model establishment for hydrogen percolation in porous rock. • Numerical simulation of the storage process of hydrogen. • Percolation laws of hydrogen in rock porous. [ABSTRACT FROM AUTHOR]

Energy Management Control Strategies (EMCS) play a significant role in improving the economy of Fuel Cell Heavy-duty Truck (FCHT). In this paper, a Single Fuzzy (S-Fuzzy) control strategy is introduced for the FCHT by considering the output characteristics of the fuel cell as well as the charging and discharging power characteristics of the power battery at the current state of charge (SOC). On this basis, the real-time difference between the current SOC and the target SOC of the power battery during the actual operation of the vehicle was further considered, the real-time correction coefficient of the fuel cell output power was introduced, and a Compound Fuzzy (C-Fuzzy) control strategy suitable for FCHT was developed. Meanwhile, the established vehicle model was verified dynamically and economically to ensure its accuracy, with the maximum speed error lower than 2%, the SOC error within 4.9%, and the relative dynamic simulation error of 1.3%. Utilizing co-simulation platforms Cruise and Matlab, the research demonstrates that the C-Fuzzy control strategy significantly outperforms the S-Fuzzy strategy, reducing Equivalent Hydrogen Consumption (EHC) by 1.63% under C-WTVC conditions and by 3.12% under CHTC-TT conditions. To counteract efficiency loss from fuel cell load fluctuations, a real-time EMCS based on C-Fuzzy control and multi-level power output was developed. Validated over a 122-km route, the real-time EMCS reduced the equivalent hydrogen consumption per 100 km of the FCHT to 10.14 kg, maintained the average fuel cell efficiency at 51.02%, and ensured stable SOC of the power battery within the predetermined target range. • Developed FCHT simulation model, validated against real data for accuracy. • Proposed S-Fuzzy control strategy for FCHT based on fuel cell and battery characteristics. • Proposed C-Fuzzy control strategy for FCHT, improving efficiency by further reducing hydrogen consumption. • Demonstrated C-Fuzzy's superiority in reducing hydrogen consumption in FCHT under typical conditions. • Evaluated EMCS in a 122 km real vehicle test, confirming fuel cell efficiency and SOC stability. [ABSTRACT FROM AUTHOR]

The time and temperature of the dispersive shear process of catalyst inks have a great influence on the agglomerate structure of the ink and the rheological properties of the ink. In this paper, three different catalyst inks were prepared at 20 °C, 30 °C and 40 °C, and tested using characterization such as rheological techniques, zeta (ξ) potential, and particle size measurements. As the temperature rises, the median particle size inside the ink at the end of shear was 400, 308.05 and 157.3 nm, and the zeta potential was −37, −33 and −25 mV, with a decrease in viscosity and a deterioration in thixotropy. The catalyst layers prepared from inks dispersed at different temperatures had the smallest cracks and the flattest surface at 30 °C, and the largest cracks, the largest contact angle, the roughest surface, and the poorest polarization properties at 40 °C. Through the comprehensive analysis of the experimental data, the fragmentation and reorganization processes of agglomerates during the internal dispersion of catalyst ink were revealed from the perspectives of time scale and temperature variation, respectively. This study provides an experimental basis for a deeper understanding of the dispersion performance of catalyst ink at different temperatures. • The variation of internal temperature of catalyst ink with shear time was studied. • The effect of shear time on catalyst inks was studied. • The effect of dispersion temperature on catalyst inks was investigated. • The relationship between rheology and catalyst layer structure was proved. [ABSTRACT FROM AUTHOR]

Hydrogen possesses a lot of potential as a renewable source of energy due to its high energy density and positive impact on the environment. It is expected to play a substantial role in various long-term applications. Considerable research effort has been directed toward identifying suitable materials for electrochemical hydrogen storage (EHS), including graphene-based materials. Graphene's exceptional properties, such as high electrical and thermal conductivity, electrochemical activity, chemical stability, and structural flexibility, make it an ideal candidate for hydrogen storage. This paper, given the profound importance of graphene in EHS and the existing knowledge gap regarding recent developmental trends and research directions, identifies current worldwide research advancements in graphene-based EHS and the impact of the modification on overall effectiveness by conducting a comprehensive search of literature published within the past five years. It presents a comprehensive comparison of various graphene-based materials, including doped graphene structures, metal hydride-graphene composites, graphene quantum dots, and graphene-alloy composites. It also outlines the main opportunities and obstacles of graphene-based materials in EHS research according to the investigated studies and provides insights and recommendations for forthcoming research in this area. [Display omitted] • Electrochemical hydrogen storage is an effective method of hydrogen storage. • Recent advancements in graphene-based electrochemical hydrogen storage were explored. • Graphene is an ideal candidate for electrochemical hydrogen storage. • Graphene modification has a significant impact on electrochemical hydrogen storage. • Insights and recommendations for future research in this field are presented. [ABSTRACT FROM AUTHOR]