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Introducing organic ligands into metal-organic frameworks (MOFs) is an effective method for preparing defective MOFs. This approach enables the fabrication of cost-effective, efficient, highly conductive, and richly active-site electrocatalysts. Herein, the defective NiMOF is synthesized via a straightforward one-pot solvothermal method by partially substituting phthalic acid (PTA) ligands with acetic acid (HOAc), which effectively regulates the micro-morphology and electronic structure of the NiMOF nanoflowers, thus creating abundant electrochemical active sites, significantly improving electronic conductivity and promoting rapid charge transfer. The resulting DE-NiMOF-0.5 nanoflowers, prepared with HOAc substitution, demonstrate excellent electrochemical performance at a current density of 10 mA cm−2, the hydrogen evolution reaction (HER) overpotential is 188 mV (Tafel slope of 175 mV dec−1), while the oxygen evolution reaction (OER) overpotential is 205 mV (Tafel slope of 37 mV dec−1). The introduction of acetic acid ligands in DE-NiMOF-0.5 not only constructs the ligand defects within the catalyst, but also increases the abundant active sites, enhancing the hydrophilicity of the catalyst and facilitating electronic transfer between the catalyst surface and the electrolyte. This study explores a strategy for preparing defective MOF catalysts through introducing modulators, providing an economically viable material pathway for electrocatalysis and opening new possibilities for designing and synthesizing efficient electrocatalysts in future research endeavors. This study introduces DE-NiMOF-0.5, a defect-rich nickel-based metal-organic framework modified with acetic acid, enhancing its electrocatalytic performance. DE-NiMOF-0.5 achieves low overpotentials of 188 mV for the hydrogen evolution reaction (HER) and 205 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm⁻2. It also demonstrates significant electrochemical stability and sustained performance during long-term cycling, making it suitable for prolonged use in alkaline water electrolysis systems. This research highlights the potential of defect engineering in MOFs for achieving cost-effective and superior hydrogen production. [Display omitted] • Ligand defects can be produced by introducing acetic acid ligand. • DE-NiMOF shows overpotentials of 188 mV (HER) and 205 mV (OER) at 10 mA cm⁻2. • The catalyst showed remarkable electrochemical stability and sustained performance. [ABSTRACT FROM AUTHOR]

We texture the Ni electrodes by nanosecond lasers under different conditions and study their electrochemical performance for hydrogen evolution reaction through alkaline water electrolysis. The parameters we vary are the ambient gas (air, N 2 , and Ar) and laser wavelength (1064 or 355 nm), focal length of the f-θ lens (160 and 63 mm), laser power, and beam overlapping. Using a 1 M KOH electrolyte at room temperature we find that the Ni electrode textured by the 355 nm laser in N 2 gas with the f-θ lens of focal length 160 mm shows the best electrochemical performance. The attained overpotential at the current density of −200 mA/cm2 and Tafel slope are 275 mV and 78 mV/dec, respectively. Our results demonstrate that nanosecond laser texturing is a high-speed and cost-effective technique which is industrially suitable to fabricate efficient electrodes for hydrogen evolution reaction. • Nanosecond laser texturing of electrode produces hierarchical micro/nanostructures. • Morphology of the textured surface strongly depends on the texturing parameters. • Choice of laser wavelength and ambient gas is important to achieve high HER. • Too much laser-texturing results in deep microstructures to spoil the HER activity. [ABSTRACT FROM AUTHOR]

In the context of renewable energy, dynamic control is crucial for large-scale alkaline water electrolysis systems. Under traditional Proportional-Integral-Derivative (PID) control, the system's temperature and impurity levels may exceed safe limits during sudden load changes, compromising system safety. Therefore, this study proposes a control strategy based on mathematical models of system temperature and impurities, including Model Predictive Control (MPC) for temperature and Optimal Curve Tracking (OCT) for impurities. The MPC controller offsets the disturbances in temperature caused by current fluctuations through state prediction, while the OCT controller ensures that impurity levels remain within safe limits. Real-time application of these control strategies is achieved through MATLAB-PLC communication, validating controller performance. Experimental results show that the MPC controller exhibits excellent dynamic response and stability in controlling the stack temperature, with a maximum temperature peak deviation of only 2.9 K and a temperature fluctuation range of 5.9 K. This represents a reduction of 1.6 K in peak deviation compared to traditional PID controllers and significantly decreases the temperature fluctuation range. The OCT controller also demonstrates good safety and stability in controlling hydrogen to oxygen (HTO) impurity levels, consistently maintaining the HTO content at the set upper limit of 1.5%, thereby expanding the safe operational range of the system and reducing the need for frequent adjustments to the system setpoints. • Established thermal dynamic and steady-state impurity models for the system. • Proposed new temperature and impurity control strategies for chemical production. • Proposed a MPC temperature controller and an OCT impurity controller. • Implemented a real-time control system with MATLAB-PLC communication. • Enhanced system stability and expanded operating margins. [ABSTRACT FROM AUTHOR]

This work investigates the optimal design and operation of an alkaline water electrolysis plant fed by renewable electricity. At the basis of this investigation lies a mathematical model that is developed to capture essential mechanisms regarding gas purity and temperature constraints. This model is optimized for maximized hydrogen production given varying power inputs and design variations. Resulting operational profiles are then weighted with realistic wind power data, allowing for a novel framework in which mechanistic models of different scales are combined to predict annual hydrogen production and online-factors. The highest online-factors are achieved with independent power supplies, which, for degraded plants, results in the largest annual production increase of all design variations (up to 9%). Designs facilitating flexible pressure operation show the largest improvement potential for novel plants, increasing the production rate by up to 4.5%. [Display omitted] • Development of modeling and optimization framework for alkaline electrolysis plant. • Investigation of BoP design on load range and utilization of wind power. • HTO related load limit reduced by flexible pressure or individual power supplies. • Flexible pressure operation increases production most (4.5%) for novel plant. • Individual power supplies increase production most (9%) for degraded plant. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis is the promising technical pathway of large‐scale green hydrogen production. However, its hydrogen evolution reaction (HER) is hindered by the alkaline environment, leading to slow H2O splitting kinetics, especially for NiMoCu alloy catalysts which are considered potential alkaline HER catalysts. In this work, the Ru‐substrate modified NiMoCu20 porous electrode is designed by a continuous multistep electrodeposition method. It shows the good alkaline HER performance at the high current density of 1000 mA cm−2, which is attributed to the synergistic charge‐reconfiguration effects between Ru‐substrate and NiMoCu alloy by density functional theory (DFT) calculations and in situ Raman spectra analysis. It indicates that the Ru‐substrate is capable of encouraging H‐OH* bond breakage and optimizing transition‐state H* adsorption. Further, the overall water electrolysis results of the alkaline water electrolysis cell (30 wt% KOH) at 70 °C show that it has good performance at the large current density of 1000 mA cm−2 with 2.05 V and good stability at 600 mA cm−2 up to 500 h. It provides the possibility of designing the high‐performance HER electrode from the view of industrial applications. [ABSTRACT FROM AUTHOR]

Hydrogen is considered a very clean and highly available renewable energy resource for the future. Water electrolysis (WE) is a conspicuous promising technology to produce hydrogen on a large scale, without generating carbon dioxide. In this study, we prepared bimetallic NiFe-based metal–organic frameworks (MOFs) integrated with CNTs (NiFe–BTC@CNTs) as highly efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline water electrolysis. Combining NiFe MOFs and CNTs significantly enhanced the electrochemical performance and structural integrity of the catalyst. The NiFe–BTC@CNT (30 wt% CNTs) demonstrates a significant low overpotential of 230 mV at 10 mA·cm⁻2, superior catalytic activity with a Tafel slope of 36 mV·dec⁻1, and excellent stability under both constant and dynamic operating conditions. These unique characteristics are attributed to the high surface area and abundant active sites provided by the bimetallic MOF structure, combined with the exceptional electrical conductivity and mechanical strength of CNTs. Furthermore, the integration of CNTs improves the dispersion while preventing the agglomeration of MOF particles, ensuring a more uniform and accessible active surface area. This research highlights the potential of the NiFe–BTC@CNT catalysts as high-performance durable electrocatalysts for sustainable hydrogen production, offering a significant advance in the development of advanced materials for energy conversion and storage applications. [Display omitted] • Bimetallic Ni- and Fe-based MOFs are synthesized by the intergradation with CNTs. • The NiFe–BTC@CNT shows synergistic catalytic performance and structural integrity. • The NiFe–BTC@CNT exhibits low overpotential of 230 mV at 10 mA cm⁻2 for OER. • It shows highly durable operation, even under harsh dynamic operation conditions. [ABSTRACT FROM AUTHOR]

Binder plays a crucial role in constructing high‐performance electrodes for water electrolysis. While most research has been focused on advancing electrocatalysts, the application of binders in electrode design has yet to be fully explored. Herein, the in situ incorporation of polytetrafluoroethylene (PTFE) as a multifunctional binder, which increases electrochemical active sites, enhances mass transfer, and strengthens the mechanical and chemical robustness of oxygen evolution reaction (OER) electrodes, is reported. The NiFe‐LDH@PTFE/NF electrode prepared by co‐deposition of PTFE with NiFe‐layered double hydroxide onto nickel foam demonstrates exceptional long‐term stability with a minimal potential decay rate of 0.034 mV h−1 at 500 mA cm−2 for 1000 h. The alkaline water electrolyzer utilizing NiFe‐LDH@PTFE/NF requires only 1.584 V at 500 mA cm−2 and sustains high energy efficiency over 1000 h under industrial operating conditions. This work opens a new path for stabilizing active sites to obtain durable electrodes for OER as well as other electrocatalytic systems. [ABSTRACT FROM AUTHOR]

Creating innovative catalysts utilizing nonprecious metals for the electrocatalytic hydrogen evolution reaction (HER) poses a significant difficulty. We present a cobaloxime (Cox) complex having pyridine (2-Cox) and tetrafluorophenyl-thio-pyridine (4-Cox) functional groups, which contains a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) moiety. This combination serves as a catalyst for proton reduction and is immobilized onto reduced graphene oxide (rGO) by π–π stacking between the cobaloxime complex and rGO. Moreover, the unique complex's structures were determined through the application of ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The electrocatalytic activity of the two rGO/2-Cox and rGO/4-Cox electrodes towards hydrogen (H 2) were examined under both alkaline and acidic conditions. The cobaloxime-modified rGO electrodes demonstrate superior electrocatalytic performance for the HER under acidic conditions compared to alkaline conditions. The overpotential at a current density of 10 mA cm−2 for rGO/2-Cox in 0.5 M H 2 SO 4 is −0.342 V, which is notably lower than the overpotential of rGO/4-Cox (−0.496 V). The Tafel slope for the rGO/2-Cox electrode in a 0.5 M H 2 SO 4 solution is 111 mV.dec−1, but for the rGO/4-Cox electrode it is 156 mVdec−1. This discrepancy suggests that the rGO/2-Cox electrode demonstrates better performance in the HER compared to the rGO/4-Cox electrode. • Two different BODIPY-cobaloxime complexes were synthesized. • These combinations are immobilized on reduced graphene oxide by π-π stacking. • The electrocatalytic activity of these structures towards hydrogen was studied. • 2-Cox structure exhibited superior electrocatalytic performance for HER. • These catalysts have the potential to be used in various energy applications. [ABSTRACT FROM AUTHOR]

Ti3C2, one typical MXene, has great potential to be coupled with various transition metals. Herein, a novel and effective catalyst is developed by synergistically loading VCoCOx onto Ti3C2‐modified nickel foam (VCoCOx–Ti3C2@NF). Field emission scanning electron microscope and high‐resolution transmission electron microscopy are employed to characterize the morphology and structure. As expected, the catalyst optimized by response surface methodology attains overpotentials of 290 and 64 mV and Tafel slopes of 82 and 79 mV dec−1 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. By using the bifunctional VCoCOx–Ti3C2@NF catalyst, the water splitting current density achieves 10 mA cm−2 in 1.0 mol L−1 KOH electrolyte at cell voltage of 1.52 V, comparable with the noble metal electrolyzer Pt@C@NF||RuO2@NF (1.57 V). Furthermore, the resulting catalyst exhibits excellent cycling durability after 120 h of continuous catalysis, which retains 103.8% and 105.4% of potential (V vs reversible hydrogen electrode) for OER and HER, respectively. Density functional theory calculation reveals that the Gibbs free energy barriers for the OER and HER intermediates are reduced due to the integration of VCoCOx with Ti3C2@NF. The fabricated VCoCOx–Ti3C2@NF catalyst is a promising electrochemical material for clean energy production. [ABSTRACT FROM AUTHOR]

Developing cost-efficient catalysts with high efficiency for water splitting has been considered as large challenge. Herein, the bulk high entropy alloys (HEAs) are fabricated through the vacuum induction melting, which could be beneficial to solving the above issues. At the same time, it also enhances the electrocatalysts activity and stability. The alloy composition is discovered to be crucial in the both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) activity enhancements with the CoCrFeNiAlMo bulk HEA catalyst combination providing the exceptional catalytic activities. Forming the CoCrFeNiAlMo bulk HEA catalyst also significantly promotes the electrocatalytic cycling stabilities. Hence, the CoCrFeNiAlMo bulk HEA catalyst displays a small overpotential (261 mV @ 50 mA cm−2) and a corresponding Tafel slope (48.66 mV dec−1) for the OER in a 1.0 M KOH electrolyte. For HER, CoCrFeNiAlMo bulk HEA catalyst also possess a relatively small overpotential. Furthermore, it exhibits a relatively small cell voltage of 1.83 V at 50 mA cm−2 and superior durable for 14 h. This study presents a universal pathway for preparing sustainable high efficiency electrocatalysts, it demonstrates that the bulk HEAs have the potential to be effective catalysts in alkaline environments. [Display omitted] • Cost-effective bulk HEAs electrocatalysts are fabricated. • CoCrFeNiAlMo catalyst shows a low overpotential for OER. • Multicomponent property of the HEAs promotes catalytic activities. [ABSTRACT FROM AUTHOR]

The efficiency of hydrogen production from water electrolysis is limited by the sluggish kinetics of the Oxygen Evolution Reaction (OER), necessitating catalytic material to avoid the high overpotentials. This study investigates LaNiO 3 as a promising electrocatalyst for the OER in Alkaline Water Electrolysis selected for its cost-effectiveness and easy scale-up. LaNiO 3 , prepared by a co-precipitation method, shows good OER activity and electrochemical stability. Operando X-Ray Absorption Spectroscopy (XAS), reveals a crucial role of the Ni(II)/Ni(III) redox couple. Notably, a layer of a Ni(II) compound formed at the catalyst surface is oxidized under anodic potentials and possibly becomes the active sites for the adsorption of OH− and for the OER reaction. High resolution transmission electron microscopy confirms the formation of a defective outer layer during operation, indicating the presence of disordered structure on the surface of the electrocatalyst, which increases the number of active sites for the OER. • High OER activity for LaNiO 3 prepared by a low-cost, easy scalable co-precipitation method. • The formation of surface reduced Ni(II) sites was detected. • Operando XAS shows that fresh, active Ni(III) sites form during the OER. • HR-TEM shows that active sites dynamics cause notable changes in the surface structure. [ABSTRACT FROM AUTHOR]

Heterogeneous molecular cobalt (Co) sites represent one type of classical catalytic sites for electrochemical oxygen evolution reaction (OER) in alkaline solutions. There are dynamic equilibriums between Co2+, Co3+ and Co4+ states coupling with OH−/H+ interaction before and during the OER event. Since the emergence of Co2+ sites is detrimental to the OER cycle, the stabilization of high‐valent Co sites to shift away from the equilibrium becomes critical and is proposed as a new strategy to enhance OER. Herein, phosphorus (P) atoms were doped into reduced graphene oxide to link molecular Co2+ acetylacetonate toward synthesizing a novel heterogeneous molecular catalyst. By increasing the oxidation states of P heteroatoms, the linked Co sites were spontaneously oxidized from 2+ to 3+ states in a KOH solution through OH− ions coupling at an open circuit condition. With excluding the Co2+ sites, the as‐derived Co sites with 3+ initial states exhibited intrinsically high OER activity, validating the effectiveness of the strategy of stabilizing high valence Co sites. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are critical processes in water splitting, yet achieving efficient performance with minimal overpotential remains a significant challenge. Although NiFe-based catalysts are widely studied, their performance can be further enhanced by optimizing the interaction between the catalyst and the substrate. Here, we present a detailed investigation of NiFe-modified graphite electrodes, comparing the effects of compressed and expanded graphite substrates on catalytic performance. Our study reveals that substrate geometry plays a pivotal role in catalyst distribution and activity, with expanded graphite facilitating more effective electron transfer and active site utilization. Additionally, we observe that increasing the NiFe loading leads to only modest gains in performance, due to catalyst agglomeration at higher loadings. The optimized NiFe–graphite composites exhibit superior stability and catalytic activity, achieving lower overpotentials and higher current densities, making them promising candidates for sustainable hydrogen production via alkaline electrolysis. [ABSTRACT FROM AUTHOR]

Developing high‐efficiency alkaline water splitting technology holds great promise in potentially revolutionizing the traditional petrochemical industry to a more sustainable hydrogen economy. Importantly, the oxygen evolution reaction (OER) accompanied at the anode is considered as a critical bottleneck in terms of both complicated mechanism and sluggish kinetics, requiring rational design of OER electrocatalysts to elucidate the structure‐performance relationship and reduce the applied overpotential. As a benchmarked non‐precious metal candidate, NiFe‐based electrocatalysts have gained enormous attention due to low‐cost, earth‐abundance, and remarkable intrinsic OER activity, which are expected to be implemented in industrial alkaline water splitting. In this contribution, a comprehensive overview of NiFe‐based OER electrocatalysts is provided, starting with fundamental mechanisms, evaluation metrics, and synthetic protocols. Subsequently, basic principles with corresponding regulatory strategies are summarized following the sequence of substrate‐catalyst‐electrolyte design of efficient and robust NiFe‐based electrocatalysts toward industrial‐scale deployment. Perspectives on remaining challenges and instructive opportunities in this booming field are finally discussed. [ABSTRACT FROM AUTHOR]

This paper presents the preparation and performance evaluation of two closed-loop nickel-based catalysts. The (hydro)oxide coatings of nickel-molybdenum and nickel-iron were electrodeposited onto industrial nickel meshes, which were subsequently used as the cathode and anode (NiMo@NM and NiFe@NM) in alkaline water electrolysis. Both catalysts formed a fully closed-loop configuration, surrounding each nickel wire on the nickel mesh, thereby enhancing the bonding strength with the substrate. The NiMo@NM||NiFe@NM assembly achieved a current density of 200 mA cm−2 at a cell voltage of only 1.91 V and room temperature, maintaining this level of performance for over 280 h. A single-stack flow cell was used to examine the changes in cell voltage in relation to temperature, current density, and electrolyte flow rate and concentration. The specific energy consumption for hydrogen production can be reduced to 4.1 kWh Nm−3 (H2) under near-industrial conditions (70 °C, 6 M KOH, 400 mA cm−2). We hope that this study can help bridge the gap between catalyst studies and practical industrial applications. [ABSTRACT FROM AUTHOR]

A new type of separation materials for alkaline water electrolyzers has been obtained: a diaphragm synthesized by the phase inversion method and a multilayer microfilm membrane with zirconium hydroxide hydrogel as a hydrophilic filler. Experimental data on their porosity, electrical conductivity, and gas density, as well as the results of their tests as part of an alkaline electrolyzer battery are presented in comparison with a porous diaphragm based on polysulfone with a hydrophilic filler (TiO2), synthesized by the traditional phase inversion method. The advantages and disadvantages of new materials are assessed, and ways for further research and development are determined. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive safety assessment of hydrogen production using Alkaline Water Electrolysis (AWE). The study utilizes various risk assessment methodologies, including Hazard Identification (HAZID), What-If analysis, Fault Tree Analysis (FTA), Event Tree Analysis (ETA), and Bow Tie analysis, to systematically identify and evaluate potential hazards associated with the AWE process. Key findings include the identification of critical hazards such as hydrogen leaks, oxygen-related risks, and maintenance challenges. The assessment emphasizes the importance of robust safety measures, including preventive and mitigative strategies, to manage these risks effectively. Consequence modeling highlights significant threat zones for thermal radiation and explosion risks, underscoring the need for comprehensive safety protocols and emergency response plans. This work contributes valuable insights into hydrogen safety, providing a framework for risk assessment and mitigation in hydrogen production facilities, crucial for the safe and sustainable development of hydrogen infrastructure in the global energy transition. • Comprehensive safety assessment of hydrogen production via Alkaline Water Electrolysis. • Identification of critical hazards including hydrogen leaks and oxygen-related risks. • Consequence modeling for unignited hydrogen releases and jet fire scenarios. • Emphasis on robust safety protocols and emergency response measures. • Provides practical insights for risk mitigation in hydrogen production facilities. [ABSTRACT FROM AUTHOR]

Energy losses and purity of product gases in alkaline water electrolysis strongly depend on properties of a separator positioned between the electrodes. This paper reports on heterogeneous separators based on microporous polysulfone membranes modified by graft co-polymerization of acrylic acid. After neutralization with KOH, the pores of the modified membranes were filled with potassium polyacrylate, a superabsorbent material forming hydrogel upon intake of an aqueous electrolyte. Under electrolysis conditions of 50 °C and atmospheric pressure, increasing amount of hydrogel in pores suppresses hydrogen permeability without apparent reduction of ionic conductivity. We have identified the product of ionic resistance and hydrogen flux as a suitable parameter to compare performance of separators of various thickness. In terms of this parameter, present separators surpass the performance of Zirfon™ Perl UTP 500 tested under the identical conditions. Ex-situ aging test in 30 wt% KOH at 60 °C has revealed preservation of high wettability for up to 1340 h. [Display omitted] • Graft co-polymerization of acrylic acid is achieved on microporous polysulfone membranes. • Modified membranes exhibit high ionic conductivity and low hydrogen permeability under electrolysis conditions at 50 °C. • High wettability is retained in KOH electrolyte at 60 °C for 1340 h. [ABSTRACT FROM AUTHOR]

A comprehensive model based on CFD modelling as well as AI/ML based modelling for an alkaline water electrolysis (AWE) cell is presented. A single cell 2D multiphase CFD model is solved in COMSOL Multiphysics 6.1® and is successfully validated with the experimental results for different operating conditions. The CFD model accurately computes the concentration and flow profiles of produced oxygen and hydrogen gases, the movement of the bubbles, and turbulence within the cell as well as the impact of current density, electrolyte flow rate and electrode-diaphragm distance. Further, integrating the CFD model with a neural network model enhances its potential for better cell design and performance. Multiple inputs and single output (MISO) artificial neural network (ANN) models are developed to predict the performance of the AWE cell. The ANN models are trained using the Levenberg-Marquardt algorithm, which operates as a feed-forward back-propagation network. The trained ANN models accurately predicts the complex relationships between input parameters (temperature, initial current density, and electrolyte weight concentration) and output parameters (actual current density and cell voltage) with an R2 value of 0.999 for both the outputs. This integrative CFD and ANN approach provides a comprehensive understanding of the AWE cell's behavior, further optimizing its design for efficient hydrogen production, offering a robust process that minimizes both computational resources and time as well as contributes for the scale up of the process. [Display omitted] • A comprehensive model based on CFD and ANN modeling for an alkaline water electrolysis (AWE) cell is presented. • The 2D multiphase CFD model is successfully validated with the experimental results for different operating conditions. • MISO models are developed to predict the performance of the AWE cell. • The trained ANN model was able to predict the input/output relationship with high accuracy. [ABSTRACT FROM AUTHOR]

To meet the rising demand for green hydrogen, efficient alkaline water electrolysis demands highly active and low‐cost electrocatalysts for the oxygen evolution reaction (OER). We address this issue by focusing our work on optimizing the conditioning of promising Ni‐(Fe)‐based electrodes to improve their electrocatalytic performances. Systematic parameter variation for cyclic voltammetry conditioning revealed that a large potential window, low scan rate, and a high number of cycles result in improved activation. If the conditioning time is fixed, a high scan rate was found beneficial. A remarkable 47±6 mV potential drop at 10 mA cm−2 was achieved for Ni70Fe30 when conditioning between −0.35–1.6 V at 100 mV s−1 for just 30 min. We could demonstrate that this activation persisted over 100 h at 100 mA cm−2, underscoring its enduring efficacy. We suggest that this activation effect results from the growth of a hydrous hydroxide layer, which is supported by energy dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy. Fe incorporation or dissolution played only a minor role in the differences in electrode activation, as demonstrated by variation of the Fe content in the electrolyte. Our work stresses the importance of conditioning in enhancing OER performance and explores how to improve the catalysts′ effectiveness by tailoring oxides. [ABSTRACT FROM AUTHOR]

Green hydrogen is typically produced by water electrolysis. In this process, water is split into hydrogen and oxygen by an electric current. Different technologies exist to produce hydrogen by electrolysis, including the four best recognized: Anion Exchange Membrane (AEM), Solid Oxide Electrolysis Cell (SOEC), Polymer Electrolyte Membrane (PEM) and Alkaline Water Electrolysis (AWE). While the latter two are commercially available, SOEC shows promise for efficient hydrogen production, and AEM combines advantages from both AWE and PEM systems. However, the most mature technology remains the most mature and cost-effective technology for industrial and large-scale hydrogen production. This review provides a comprehensive overview of recent advances in alkaline water electrolysis (A-WE) for hydrogen production, including a comparative assessment of the four commonly used electrolysis technologies. The paper covers the current status, recent research advances, and commercialization challenges of A-WE technology, offering insight into its potential and outlining future research directions. • The paper comprehensively assesses A-WE, PEM, SOEC, and AEM technologies for green hydrogen production. • Alkaline Water Electrolysis (A-WE) is the most cost-effective and mature technology for large-scale hydrogen production. • A-WE's limitations include low current density, corrosivity, gas permeation, slow response, and sensitivity to impurities. • Advanced materials, optimized electrolytes, membranes, and innovative electrode designs enhance A-WE performance. • A-WE market saw 6.5% CAGR growth, driven by sustainable energy demand despite supply chain and geopolitical challenges. [ABSTRACT FROM AUTHOR]

The concentration of hydrogen in oxygen (HTO) is a crucial factor in determining the load limit of alkaline water electrolysis (AWE) due to the risk of explosion with high HTO levels. In this study, we analysed the impact of circulating electrolytes, carrying dissolved gas, on HTO in a home-designed zero-gap alkaline water electrolysis system, operating at atmospheric pressure and constant temperature. By comparing the experimental results from mixed and separated cycles, we found that the amount of dissolved hydrogen in the electrolyte significantly contributes to HTO. We then developed a theoretical model to predict HTO values and experimentally confirmed a linear relationship between the HTO and the ratio of electrolyte circulation to gas production (Q L / Q O 2 ). Based on this evidence, we proposed a new electrolyte circulation control strategy that reduces the HTO value by as much as 63.56%. These findings could help overcome the load limit of alkaline water electrolysis systems, which is crucial for their large-scale application. [Display omitted] • Electrolyte circulation contributes significantly to HTO. • Circulating electrolytes carries dissolved hydrogen that increases HTO. • Optimization of electrolyte circulation helps to reduce HTO by up to 63.56%. [ABSTRACT FROM AUTHOR]

Electrocatalytic water decomposition couple with renewable energy is considered as a green and sustainable method for hydrogen production. However, the development of non-precious metal bifunctional catalysts remains one of the major bottlenecks in electrochemical water decomposition, hindering the key challenges for its commercial application. In this paper, we report a simple and rapid synthesis of an iron metal-organic skeleton (Fe-MOF) precursor at room temperature via the flash nanoprecipitation (FNP) technique. The precursor reacts with SiCl 4 to derive a Si-Fe-MOF catalyst with mesoporous structure. The electrochemical performance tests reveal that compared to Fe-MOF, Si-Fe-MOF exhibits significantly better performance, with overpotentials of 181 mV and 269 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) respectively (while Fe-MOF has overpotentials of 297 mV for HER and 337 mV for OER) at a current density of 10 mA cm−2, and it possesses superior stability, respectively, at 10 mA cm−2, and has superior stability. Meanwhile, Si-Fe-MOF is used as a bifunctional catalyst with a full hydrolysis voltage of 1.62 V. It is found by in situ Raman spectroscopic characterization that Si-Fe-MOF is converted from Fe metal sites to more active FeOOH during the OER process. DFT calculations show that the doping of Si atoms in Si-Fe-MOF optimize the electronic structure of the catalyst and optimize the reactive intermediates' adsorption. • Si-doped Fe-MOF with improved electrolytic water performance. • The mesoporous structure of Si-Fe-MOF provides more active sites. • Revealing the formation of intermediate hydroxylated iron substances. • Silicon doping to optimize the adsorption energy of intermediates. • SiCl 4 enables silicon doping and promotes waste utilisation. [ABSTRACT FROM AUTHOR]

The polyphenylene sulfide (PPS) mesh-based polysulfone (PSF)-zirconia (ZrO 2) composite diaphragm represents a new type of high-performance diaphragm for alkaline water electrolysis hydrogen production, offering low area resistance and high chemical stability. In this study, composite diaphragms with excellent performance are prepared using preheated compression molding, phase inversion precipitation, and vacuum stirring degassing techniques. The comprehensive performance of the prepared diaphragm is compared to that of the commercial Zirfon® diaphragm. The results indicate that the prepared composite diaphragm, with a thickness of 140 μm, exhibits excellent performance. Compared to the Zirfon® UTP 220 diaphragm, the ultra-thin composite diaphragm demonstrates a reduction in area resistance from 0.19 Ω cm2 to 0.1 Ω cm2, an increase in bubble point pressure from 2.31 bar to 2.46 bar, and a voltage of 1.84 V at 1000 mA cm−2. The incorporation of the PPS mesh resulted in a substantial improvement in tensile strength. The application of an ultra-thin composite diaphragm based on PPS mesh can significantly enhance the efficiency of hydrogen production via alkaline water electrolysis. [Display omitted] • Hot-pressing, phase inversion, and vacuum stirring degassing techniques are adopted. • Sponge pore structure improves the bubble point pressure of composite diaphragms. • Ultra-thin composite diaphragm with low area resistance and cell voltage. • It can work continuously and stably in a high-intensity electrolysis environment. [ABSTRACT FROM AUTHOR]

The quest for efficient green hydrogen production through Alkaline Water Electrolysis (AWE) is a critical aspect of the clean energy transition. The hydrogen evolution reaction (HER) in alkaline media is central to this process, with the performance of electrocatalysts being a determining factor for overall efficiency. Theoretical studies using energy-based descriptors are essential for designing high-performance alkaline HER electrocatalysts. This review summarizes various descriptors, including water adsorption energy, water dissociation barrier, and Gibbs free energy changes of hydrogen and hydroxyl adsorption. Examples of how to apply these descriptors to identify the active site of materials and better design high-performance alkaline HER electrocatalysts are provided, highlighting the previously underappreciated role of hydroxyl adsorption-free energy changes. As research progresses, integrating these descriptors with experimental data will be paramount in advancing AWE technology for sustainable hydrogen production. [ABSTRACT FROM AUTHOR]

The efficient production and sustainable operation of water electrolysis hydrogen production equipment within renewable energy systems, characterized by intermittency and volatility, necessitates dynamic simulation for the development of optimized control systems. This paper proposes the application and modification of a data-driven deep-learning model to simultaneously simulate the thermal and electrochemical responses of an alkaline water electrolyzer (AWE), yielding exceptional performance and versatility. By utilizing 4840 h of comprehensive experimental data, the causal relationships among electrolyzer operating parameters are resolved, classifying them into set values and response values for the proposed dynamic model. The model architecture is based on an attention mechanism and designed with hybrid input. Notable enhancements include embedding flow-leveraged polarization function, creating set-value cross-attention, and adopting probability-sparse attention, all of which are validated through both the validation and simulation results. Extensive exploration of various structural and training parameters leads to the selection of the best-performing model. When applied to simulation across all experimental data, the median mean percentage absolute error of the optimal model in cell voltage is a mere 1.3%, while the error in temperature is only 3.5%. Moreover, under typical operating conditions, the simulation error for both voltage and temperature remain below 2%, highlighting the outstanding dynamic modeling and simulation capabilities. These results demonstrate the potential of the proposed model for future hydrogen energy applications in dynamic control and operational optimization within renewable energy system for higher performance and better conversion efficiency. • Deep-learning model for dynamic thermoelectric simulation of water electrolyzers. • Flow-leveraged polarization function and set-value cross-attention mechanism. • Excellent accuracy, thermoelectric error of 3.5% and 1.3%, respectively. • Insights for optimizing control strategies of electrolyzer for higher efficiency. [ABSTRACT FROM AUTHOR]

Commercial alkaline water electrolysers typically operate at 80 °C to minimize energy consumption. However, NiFe‐based catalysts, considered as one of the most promising candidates for anode, encounter the bottleneck of high solubility at such temperatures. Herein, we discover that the dissolution of NiFe layered double hydroxides (NiFe‐LDH) during operation not only leads to degradation of anode itself, but also deactivates cathode for water splitting, resulting in decay of overall electrocatalytic performance. Aiming to suppress the dissolution, we employed oxyanions as inhibitors in electrolyte. The added phosphates to the electrolyte inhibit the loss of NiFe‐LDH active sites at 400 mA cm−2 to 1/3 of the original amount, thus reducing the rate of performance decay by 25‐fold. Furthermore, the usage of borates, sulfates, and carbonates yields similar results, demonstrating the reliability and universality of the active site dissolution inhibitor, and its role in elevated water electrolysis. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis (AWE) operated by surplus electricity is suitable for producing green hydrogen in Nepal. Simulation models are built using DWSIM software for AWE, multistage compression, and the Organic Rankine Cycle (ORC). The AWE system's Capital Expenditure (CAPEX) is determined to be $47 million and Operational Expenditure (OPEX) of $7.65 million/year. The storage system, including the multistage compression system and Type IV cylinders, has a CAPEX of $52 million and an OPEX of $17 million/year. The ORC has a CAPEX of $500,000 and an OPEX of $200,000/year. The thermal power generated from AWE and multistage compression can be converted to electricity by the ORC and supplied to the AWE system. This process decreases the Levelized Cost of Hydrogen (LCOH) from $3.5141/kg over 5 years to $3.4725/kg over 25 years. The techno-economic analysis performed confirms the feasibility of implementing these plants in Nepal. • A 10 MW AEL and multistage compression model are connected to the ORC. • Hydrogen produced by AEL is compressed by using a multistage compressor. • The ORC's efficiency relies primarily on the quantity of organic compound used. • Values of LCOH decrease with years of operation. • The storage method can be a good option for storing hydrogen produced in Nepal. [ABSTRACT FROM AUTHOR]

This study investigated the impact of acetone on the electrochemical behavior of polycrystalline platinum electrodes in 0.1 M NaOH solution, with respect to the kinetics of hydrogen and oxygen evolution reactions (HER and OER) and indirectly to the underpotential deposition of hydrogen (UPDH). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were employed to analyze these processes for acetone concentrations ranging from 1.0 × 10−6 to 1.0 × 10−3 M. The addition of (CH3)2C=O enhanced the catalytic efficiency of alkaline water splitting, which was believed to be a result of a significant reduction in the surface tension phenomenon (due to mutual interaction of acetone and water molecules), thus considerably facilitating hydrogen bubble detachment from the Pt electrode. Key findings in this work are described with respect to facilitation of both the HER and the OER reactions' kinetics by the presence of acetone (also undergoing Pt electroreduction over the potential range for UPDH) in the working solution, without an electrode surface poisoning effect. The latter implies significant opportunities for traces of organic additives into alkaline electrolyte to improve the industrial alkaline water electrolysis process. [ABSTRACT FROM AUTHOR]

To obtain highly efficient yet easily produced water-splitting cathodes, Ni-MoO2 composite coatings were electrodeposited at a Ni foam substrate with an open-pore structure, pore size of 450 µm, in a Watts-type bath. The concentration of MoO2 particles (about 100 nm) was varied, while the intensive mixing of the solution was provided by air bubbling with 0.5 L min−1. Electrodeposition was performed at different constant current densities at room temperature. The morphology and composition of the coatings were investigated by SEM and EDS. The hydrogen evolution reaction (HER) was tested in KOH of different concentrations, at several temperatures, in a three-electrode H-cell by recording polarization curves and EIS measurements. The lowest achieved HER overpotential was −158 mV at −0.5 A cm−2. Up-scaled samples, 3 × 3.3 cm2, were tested in a single zero-gap cell showing decreasing cell voltage (from 2.18 V to 2.11 V) at 0.5 A cm−2 over 5 h in 30% KOH at 70 °C with electrolyte flow rate of 58 mL min−1. Compared to pure Ni foams used as both cathode and anode under the same conditions, the cell voltage is decreased by 200 mV, showing improved electrode performance. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis (AWE) systems offer a cost‐effective and scalable approach for large‐scale hydrogen production using renewable energy sources. However, their susceptibility to load fluctuations, particularly the reverse‐current (RC) phenomenon during shutdown events, poses a significant challenge to the long‐term stability and scalability of these systems. Herein, a catalytic approach for enhancing the RC tolerance in AWE systems by using Pb‐decorated Ni cathode catalysts (Pb/Ni) is introduced. The oxidation of Pb/Ni by repeated RC lowers the electromotive force for the reverse current operation, and consequently, imparts RC tolerance. Intriguingly, contrary to the expectation that the decoration with lead, an inert material for the hydrogen evolution reaction (HER), will interfere with the hydrogen generation of the Ni catalyst, the presence of Pb on the Ni cathode after the RC flow promotes both the proton desorption and water‐dissociation steps, improving the HER activity. Furthermore, the AWE stack testing with Pb/Ni catalysts is perfectly operated, demonstrating remarkably enhanced RC tolerance during startup/shut‐down (SU/SD) testing protocol. This paper presents a new strategy for mitigating the AWE performance degradation induced by RC flow and for achieving Pb/Ni catalysts with improved operational durability against RC flow in AWE systems. [ABSTRACT FROM AUTHOR]

Climate change and the increasing demand for energy become major issues in public discussions today. The Paris Agreement is one of the results of such public discussions that focuses on achieving the 2050 net zero emission target. Many energy agencies have created scenarios to achieve this target. In this regard, green hydrogen is expected to have a significant role in energy transition plan. For this reason, in recent years, research related to green hydrogen production using the water electrolysis method continues to develop. The paper aimed primarily to conduct an overview of alternative technologies that can be used in producing green hydrogen with the solar energy based low temperature water electrolysis method. Secondarily, it would present information about several solar energy-based electrolysis project plans and a summary of challenges and opportunities in the development of solar energy based low temperature water electrolyzers in the future. Furthermore, to achieve commercially viable green hydrogen production, it is important to find new ideas, potential solutions, and constructive recommendations as soon as possible for further development research. This paper expectedly would be able to help initiate the development of green hydrogen production research through water electrolysis technology that is efficient, cost effective economically, and environmentally friendly. [ABSTRACT FROM AUTHOR]

Hyperbranched poly(terphenyl piperidine) with pyrene as the branched core is synthesized by co-polymerization of p-terphenyl, N-methyl-4-piperidone, and pyrene in the presence of acid. Anion exchange membranes (AEMs) with different degrees of branching are prepared by controlling the ratio of branching pyrene to backbone p-terphenyl. The chemical structure, thermal stability, mechanical feature, and ionic conductivity of the polymers are thoroughly studied. After casting, the AEMs are further applied into AEM water electrolyzers (AEMWEs) to evaluate their device performance under practical working conditions. The mechanical features and dimensional stability of AEMs have been improved by branching. The thermal stability of the AEMs is close to that of the linear control polymer-based membrane. The tensile strength of as-prepared AEMs reaches 73.5 MPa, which is 72% higher than the linear polymer-based membrane (42.8 MPa). The ionic conductivity of as-prepared AEMs reaches 78.2 mS/cm at room temperature and 168.0 mS/cm at 80 ℃. After branching, the water content (81.9% at 80 ℃) and swelling ratio (47.1% at 80 ℃) of as-prepared AEMs decrease significantly in comparison with linear control polymer-based AEM (water content: 139.2%, swelling ratio: 82.7%). In AEMWEs, the devices exhibit excellent electric current density of 1.95 A/cm² at 3 V and stable operation over 90 h. [ABSTRACT FROM AUTHOR]

Abstract Binder plays a crucial role in constructing high‐performance electrodes for water electrolysis. While most research has been focused on advancing electrocatalysts, the application of binders in electrode design has yet to be fully explored. Herein, the in situ incorporation of polytetrafluoroethylene (PTFE) as a multifunctional binder, which increases electrochemical active sites, enhances mass transfer, and strengthens the mechanical and chemical robustness of oxygen evolution reaction (OER) electrodes, is reported. The NiFe‐LDH@PTFE/NF electrode prepared by co‐deposition of PTFE with NiFe‐layered double hydroxide onto nickel foam demonstrates exceptional long‐term stability with a minimal potential decay rate of 0.034 mV h−1 at 500 mA cm−2 for 1000 h. The alkaline water electrolyzer utilizing NiFe‐LDH@PTFE/NF requires only 1.584 V at 500 mA cm−2 and sustains high energy efficiency over 1000 h under industrial operating conditions. This work opens a new path for stabilizing active sites to obtain durable electrodes for OER as well as other electrocatalytic systems.

Ti3C2, one typical MXene, has great potential to be coupled with various transition metals. Herein, a novel and effective catalyst is developed by synergistically loading VCoCOx onto Ti3C2‐modified nickel foam (VCoCOx–Ti3C2@NF). Field emission scanning electron microscope and high‐resolution transmission electron microscopy are employed to characterize the morphology and structure. As expected, the catalyst optimized by response surface methodology attains overpotentials of 290 and 64 mV and Tafel slopes of 82 and 79 mV dec−1 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. By using the bifunctional VCoCOx–Ti3C2@NF catalyst, the water splitting current density achieves 10 mA cm−2 in 1.0 mol L−1 KOH electrolyte at cell voltage of 1.52 V, comparable with the noble metal electrolyzer Pt@C@NF||RuO2@NF (1.57 V). Furthermore, the resulting catalyst exhibits excellent cycling durability after 120 h of continuous catalysis, which retains 103.8% and 105.4% of potential (V vs reversible hydrogen electrode) for OER and HER, respectively. Density functional theory calculation reveals that the Gibbs free energy barriers for the OER and HER intermediates are reduced due to the integration of VCoCOx with Ti3C2@NF. The fabricated VCoCOx–Ti3C2@NF catalyst is a promising electrochemical material for clean energy production.

Currently, a large number of studies on alkaline water electrolysis are being carried out with the aim of reducing the specific energy costs for the hydrogen evolution reaction and the oxygen evolution reaction. This work is devoted to the methods of synthesis of highly dispersed composite coating on the surface of nickel foam and the methods of the formation of bi- and ternary catalytic alloys based on molybdenum using electrochemical deposition. During the study of the samples morphological and element-by-element analyses were carried out and the activity indicators of the synthesized highly effective catalytic coatings were obtained.

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

High‐throughput experimentation, a well‐established and powerful tool in the field of heterogeneous catalysis screening, has been extended to the field of electrochemistry. A parallel and modular high‐throughput screening platform was designed, involving the development of a new modular electrochemical flow cell by the Fraunhofer Institute for Microengineering and Microsystems (IMM) in cooperation with hte GmbH and IEK‐9 / FZ Jülich GmbH. Here, this platform is introduced for alkaline water electrolysis, showing initial results that underline the flexibility, comparability, and accuracy of the experiments. [ABSTRACT FROM AUTHOR]

Industrial water electrolyzers mainly use old thyristor-based rectifiers to obtain the DC current required to run because of the low voltage level and high current requirements of the processes. These rectifiers cause significant ripple in the electrolyzer input current, leading to dynamic operation of the electrolyzer. Even though industrial-scale water electrolyzers are operated under such dynamic conditions, the effect on the electrolyzer performance is not well explored. In this study, current measurements from an industrial alkaline electrolyzer plant were used to define the common current ripple amplitude and frequency caused by the thyristor-based rectification. Based on the parameters obtained, laboratory measurements were conducted using an alkaline water electrolyzer to define the power losses incurred at various ripple amplitudes and frequencies. Additionally, the linearization of the electrolyzer current–voltage behavior as a function of frequency was studied using two electrode sets made of different materials. The laboratory measurements carried out in the study show that the ripple amplitude has a significant effect on increasing the losses, whereas the ripple frequency counteracts this. Thus, dynamic operation can have a large impact on losses, especially at partial loads, where the ripple current amplitudes increase significantly when using thyristor rectifiers. Lastly, the frequencies where the electrolyzer starts to behave linearly were observed to be at 68 Hz with the first electrode set and at 5 Hz with the second one. The considerable difference between the electrode sets indicates that the electrode materials and microstructure play a significant role in defining the electrolyzer frequency behavior. Because common thyristor-based power delivery systems operate at 300 Hz or 600 Hz, the results also imply that when modeling these systems, a linear model can be used for the electrolyzer to simplify the simulation. [Display omitted] • Large amplitude current ripple on alkaline electrolyzers is studied. • Ripple amplitude increases power losses, while frequency counteracts it. • As ripple frequency is increased, the electrolyzer starts to behave linearly. • The linear slope is determined purely based on the impedance. • At high frequencies, power usage can be determined from EIS measurement. [ABSTRACT FROM AUTHOR]

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Water electrolysis is a crucial technology in the production of hydrogen energy. Due to the escalating industrial demand for green hydrogen, the required electrode size for a traditional alkaline water electrolyzer has been increasing. Numerous studies have focused on developing highly active oxygen evolution reaction (OER) catalysts for water electrolysis. However, there remains a significant gap between the microscale synthesis of catalysts in laboratory settings and the macroscale preparation required for industrial scenarios. This challenge is particularly pronounced in the synthesis of sizable self-supported electrodes. In this work, we employed a commercially available Raney Ni-coated Ni mesh as a precursor material to fabricate a self-supported NiFe(OH)x@Raney Ni anode with a substantial dimension exceeding 300 mm through a straightforward immersion technique. The as-prepared electrode exhibited remarkable electrocatalytic OER activity, as an overpotential of only 240 mV is required to achieve 10 mA cm−2. This performance is comparable to that of NiFe-LDHs synthesized via a hydrothermal method, which is difficult to scale up for industrial applications. Furthermore, the electrode demonstrated exceptional durability, maintaining stable operation for over 100 h at a current density of 500 mA cm−2. The large-scale electrode displayed consistent overpotentials across various areas, indicating uniform catalytic activity. When integrated into an alkaline water electrolysis device, it delivered an average cell voltage of 1.80 V at 200 mA cm−2 and achieved a direct current hydrogen production energy consumption as low as 4.3 kWh/Nm3. These findings underline the suitability of electrodes for industrial scale applications, offering a promising alternative for energy-efficient hydrogen production. [ABSTRACT FROM AUTHOR]

Porous membranes play a crucial role in alkaline water electrolyzer, and addressing the urgent need for the development of membranes with enhanced ion-transferring properties and superior gas-retarding properties is of utmost importance. This work presents a simple and efficient method for preparing the superhydrophilic polyphenylene sulfide (PPS) membrane, which includes surface oxidation to generate photosensitive sulfone groups, then UV irradiation radical reaction to introduce amine groups as the reaction site, and finally covalently grafting chitosan oligosaccharide (COS) monomers containing hydrophilic groups onto the PPS surface via interfacial polymerization to form a superhydrophilic coating on the surface of fibers. The application of ATR-FTIR, XPS, and SEM has been employed to illustrate that the monomers utilized in the preparation procedure are chemically bonded to the membrane surface, resulting in the formation of a hydrophilic surface layer. The modified PPS membrane can fast adsorb water droplets, promote ion transfer and gas bubbles detachment in an alkaline solution. When used as a membrane in an alkaline water electrolyzer with a 30% KOH electrolyte solution, the cell voltage of 1.90 V at 80oC and 5000 A m−2, and the hydrogen and oxygen produced with a purity of 99.88% and 99.49%, respectively, which was better than the commercial PPS membrane, and the performance was remained essentially unchanged after 120 h of operation. As a result, the superhydrophilic PPS membrane generated by this process has a wide range of applications in alkaline water electrolysis. [Display omitted] • Superhydrophilic PPS membrane was prepared and tested in alkaline water electrolysis. • The area resistance of SHL-PPS used in the electrolyzer is 0.11 Ω cm2 (80 °C, 30% KOH). • AWE using SHL-PPS produces H 2 and O 2 with higher purities than using commercial PPS. • SHL-PPS membrane facilitates the long-term stable operation of AWE. [ABSTRACT FROM AUTHOR]

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

Although the active species induced by surface reconstruction have been extensively studied during oxygen evolution reaction (OER), it is still highly challenging to regulate and promote the reconstruction level to achieve exceptional catalytic activity and stability for realistic alkaline water electrolysis (AWE). Herein, we demonstrated that nickel mesh (NM) treated by a facile electrochemical anodization (ANM) can be easily induced into a deep reconstruction level on surface after activation, attributing to the autologous creation of a porous and amorphous NiO x (OH) y layer. Additionally, the reconstruction level can be promoted by increasing the temperature and alkali concentration of the electrolyte during the activation process. The deeply reconstructed ANM enables excellent OER performance with a low overpotential of 284 mV to achieve 10 mA/cm2, 132 mV lower than that of the NM. When combined with a Raney Ni cathode, the assembled AWE device working under industrial conditions can implement 400 mA/cm2 current at a low cell voltage of 1.79 V with a stable operation for 14 days, showing great potential in practical hydrogen production. • A deep surface reconstruction level developed based on anodized nickel mesh (ANM). • The deeply reconstructed ANM enables excellent OER performance. • The OER performance attributes to the autologous creation of NiO x (OH) y layer. • A low cell voltage of 1.79 V achieved in an industrial AWE device. [ABSTRACT FROM AUTHOR]

Design and synthesis of a low-cost, high-durable, and conductive membrane are paramount in reducing energy losses for alkaline water electrolysis (AWE), which has emerged as a promising technology for green hydrogen production. In this study, we utilize Mg(OH) 2 particles to fill the pores of a low-cost polypropylene/polyethylene (PP/PE) membrane, thereby reducing gas crossover and enhancing conductivity. This leads to the preparation of a Mg(OH) 2 -PP/PE composite membrane. When equipped in a flow-type AWE electrolyzer, this composite membrane exhibits a voltage of 1.93 V at a current density of 0.5 A cm−2 over a 100 h measurement period, which is superior to the commercial polyphenylene sulfide (PPS) membrane's voltage of 2.69 V. Furthermore, the 5000 h stability test, without any conductivity loss in the membrane, further confirms its high stability. The successful design of this composite membrane provides a new approach for high-performance AWE. Mg(OH) 2 -PP/PE composite membrane reduce the gas crossover and enhance the conductivity. The composite membrane equipped flow-type AWE electrolyzer displays a voltage of 1.93 V at a current density of 0.5 A cm−2 for over 100 h which is better than the commercial PPS membrane with 2.69 V. [Display omitted] • A low-cost Mg(OH) 2 -PP/PE composite membrane was fabricated via a simple chemical deposition method. • The Mg(OH) 2 -PP/PE composite membrane displays low gas-permeability, high conductive and hydrophily. • The Mg(OH) 2 -PP/PE composite membrane exhibits excellent alkali-resistant and mechanical strength after 5000 h test. [ABSTRACT FROM AUTHOR]

Alkaline water splitting electrocatalysts have been studied for decades; however, many difficulties remain for commercialization, such as sluggish hydrogen evolution reaction (HER) kinetics and poor catalytic stability. Herein, by mimicking the bulk‐heterojunction morphology of conventional organic solar cells, a uniform 10 nm scale nanocube is reported that consists of subnanometer‐scale heterointerfaces between transition metal phosphides and oxides, which serves as an alkaline water splitting electrocatalyst; showing great performance and stability toward HER and oxygen evolution reaction (OER). Interestingly, the nanocube electrocatalyst reveals acid/alkaline independency from the synergistic effect of electrochemical HER (cobalt phosphide) and thermochemical water dissociation (cobalt oxide). From the spray coating process, nanocube electrocatalyst spreads uniformly on large scale (≈6.6 × 5.6 cm2) and is applied to alkaline water electrolyzers, stably delivering 600 mA cm−2 current for >100 h. The photovoltaic‐electrochemical (PV‐EC) system, including silicon PV cells, achieves 11.5% solar‐to‐hydrogen (STH) efficiency stably for >100 h. [ABSTRACT FROM AUTHOR]

The effects of vertical Lorentz forces generated by an external magnetic field applied perpendicular to the inherent electric field on the oxygen evolution reaction conducted on a Ni wire are investigated using cyclic voltammetry, impedance measurements, and particle image velocimetry (PIV). Both downward and upward Lorentz forces provide smaller overpotentials than that generated in their absence. Based on a dual-bubble layer model for reactant transfer, we find that the diffusion resistance of the hydroxide ions and increased ohmic resistance (after iR correction) induced by the layer of bubbles attached to the electrode surface are most effectively alleviated by the downward Lorentz force, while the charge-transfer resistance is retained. Furthermore, the generated bubbles have smaller average diameters. By using PIV measurements, we find that stronger shear stresses induced by the faster flow of the electrolyte in the vicinity of the working electrode facilitate the detachment of bubbles from the electrode surface. [Display omitted] • Downward Lorentz force by an external magnetic field promoted the OER the most. • Downward Lorentz force disturbed the upward flow induced by charged bubbles. • Chaotic convection flow increased the shear stress acting on the electrode surface. • Shear stress drastically reduced the mass transfer resistance due to bubbles. • OER catalytic properties are not affected by the Lorentz force. [ABSTRACT FROM AUTHOR]