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The hydrophilic pore morphology and solvent diffusion within model (amphiphilic) polymer membranes are simulated by dissipative particle dynamics (DPD). The polymers are composed of a backbone of 18 covalently bonded A beads to which at regular intervals side chains are attached. The side chains are composed of linear Ap chains (i.e., –A1–A2...Ap) from which two branches, [AsC] and [ArC], split off (s ≤ r). C beads serve as functionalized hydrophilic pendent sites. The branch lengths (s + 1 and r + 1) are varied. Five repeat unit designs (with general formula A3[Ap[AsC][ArC]]) are considered: A2[A3C][A3C] (symmetric branching), A2[A2C][A4C], A2[AC][A5C], A2[C][A6C] (highly asymmetric branching), and A4[AC][A3C]. The distribution of water (W) and W diffusion through nanophase segregated hydrophilic pores is studied. For similar primary length p, an increase in side chain symmetry favors hydrophilic pore connectivity and long-range water transport. C beads located on the longer [ArC] branches reveal the highest C bead mobility and are more strongly associated with water than the C beads on the shorter [AsC] branches. The connectivity of hydrophilic (W and W + C) phases through mapped replica of selected snapshots obtained from Monte Carlo tracer diffusion simulations is in line with trends found from the W bead diffusivities during DPD simulations. The diffusive pathways for protons (H+) in proton exchange membranes and for hydronium (OH−) in anion exchange membranes are the same as for solvents. Therefore, control of the side chain architecture is an interesting design parameter for optimizing membrane conductivities. [ABSTRACT FROM AUTHOR]

Anion exchange membrane fuel cells (AEMFCs) represent a promising class of clean energy devices, with their performance being critically dependent on the efficiency of the cathode oxygen reduction reaction (ORR) catalyst. Herein, we report a highly efficient ORR catalyst based on bimetallic-doped CuMn–N–C combined with MXene and carbon nanotubes (CNT). The CuMn–N–C@MXene + CNT exhibits the half-wave potential (E 1/2) of 0.860 V and a minimal potential decay of only 4 mV after 10,000 CV cycles. These results reveal that the CuMn–N–C@MXene + CNT catalyst outperforms the conventional Pt/C catalyst in terms of both ORR activity and stability. Moreover, an AEMFC incorporating the CuMn–N–C@MXene + CNT catalyst demonstrates a power density of 317 mW cm−2 and only 2.3% performance loss after 14 h of operation. This study offers a valuable strategy for designing and synthesizing low-cost, efficient, and stable electrocatalysts for AEMFC applications. [Display omitted] • CuMn–N–C@MXene + CNT showed E 1/2 of 0.860 V and only a 4 mV day after 10,000 CV cycles. • CuMn–N–C@MXene + CNT demonstrated a power density of 317 mW cm−2 in AEMFC. • CuMn–N–C@MXene + CNT retained 97.7% of its initial current after 14 h in AEMFC. [ABSTRACT FROM AUTHOR]

Fully sustainable hydrogen production demands renewable energy sources. This study uses an approach that combines solar photovoltaic (PV) systems with batteries to tailor the energy supply to the unique demands of anion exchange membrane (AEM) electrolyzers. An open source DC-DC adjustable converter is designed, prototyped, and tested to enable an AEM to operate at its optimum efficiency without disrupting the continuous operation of existing loads. A structured operating schedule is simulated to align PV performance with AEM electrolyzer characteristics. The results show the >90% efficiency open-source converter was able to directly power the electrolyzer while taking advantage of solar energy surplus for hydrogen production. By strategically scheduling the electrolyzer to maximize output and minimize waste the system only utilizes excess solar energy. By employing this sustainable method, the study highlights a scalable solution that not only enhances the efficiency of hydrogen production, but also promotes the deployment of PV. • Surplus PV energy is used via structured AEM electrolyzer schedules for H₂ production. • 75% of AEM is PV-powered, reducing energy waste, with batteries covering the rest. • Open-source adjustable DC-DC converter ensures optimal AEM electrolyzer performance. • Custom DC-DC converter achieves 90% efficiency, cutting power loss for the electrolyzer. [ABSTRACT FROM AUTHOR]

Anion exchange membrane (AEM) water electrolysis is a promising and inexpensive solution for hydrogen production and environmental problems. Owing to its low technical proficiency, AEM electrolysis necessitates high fidelity to improve its durability, reliability, and efficiency. Therefore, a CFD-based model for AEM electrolysis was developed to analyze the three-dimensional and two-phase phenomena inside the cell. The temperature, pressure, and gas generation profiles inside the cell were studied by combining electrochemical models with mass, momentum, and heat transfer models. Parameters were estimated using the experimental data from a high-accuracy model. The results showed that the applied voltage, which determined the exothermic/endothermic mode, significantly influenced the water electrolysis performance. Specifically, in the exothermic mode, with voltages exceeding the thermo-neutral voltage (1.48 V), the amount of hydrogen generated (15.53, 25.05, and 28.82 mol/m3 at 1.6, 1.8, and 2.0 V, respectively) was higher than that in the endothermic mode (4.78 mol/m3 at 1.45 V). However, the increased gas generation caused a rapid increase in the temperature and pressure drop inside the cell, which adversely affected durability. The model developed in this study can be used in experiments of various scales to optimize serpentine designs and commercial AEM electrolysis stack developments. [ABSTRACT FROM AUTHOR]

Hydrogen electrocatalytic reactions, including the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR), play a crucial role in a wide range of energy conversion and storage technologies. However, the HER and HOR display anomalous non-Nernstian pH dependent kinetics, showing two to three orders of magnitude sluggish kinetics in alkaline media compared to that in acidic media. Fundamental understanding of the origins of the intrinsic pH effect has attracted substantial interest from the electrocatalysis community. More critically, a fundamental molecular level understanding of this effect is still debatable, but is essential for developing active, stable, and affordable fuel cells and water electrolysis technologies. Against this backdrop, in this review, we provide a comprehensive overview of the intrinsic pH effect on hydrogen electrocatalysis, covering the experimental observations, underlying principles, and strategies for catalyst design. We discuss the strengths and shortcomings of various activity descriptors, including hydrogen binding energy (HBE) theory, bifunctional theory, potential of zero free charge (pzfc) theory, 2B theory and other theories, across different electrolytes and catalyst surfaces, and outline their interrelations where possible. Additionally, we highlight the design principles and research progress in improving the alkaline HER/HOR kinetics by catalyst design and electrolyte optimization employing the aforementioned theories. Finally, the remaining controversies about the pH effects on HER/HOR kinetics as well as the challenges and possible research directions in this field are also put forward. This review aims to provide researchers with a comprehensive understanding of the intrinsic pH effect and inspire the development of more cost-effective and durable alkaline water electrolyzers (AWEs) and anion exchange membrane fuel cells (AMFCs) for a sustainable energy future. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction (eCO2R) stands as a pivotal technology for carbon recycling by converting CO2 into value‐added products. While significant strides have been made in generating multi‐carbon (C2+) products like ethylene (C2H4) and ethanol (C2H5OH) at industrial‐scale current densities with high Faradaic efficiency (FE), cathode flooding and (bi)carbonate salt accumulation remain a fundamental concern in an alkaline electrolyte. In this work, ion‐conducting polymers are used to tailor the micro‐environment mitigating cathode flooding and salt precipitation and thus, enhancing the local CO2 availability. The impact of cation and anion exchange ionomer layers, specifically Nafion and Sustainion XA‐9 are examined on overall eCO2R performance. The use of an ultra‐thin bilayer configuration significantly reduces cathode flooding and salt accumulation by ≈58% compared to commercial anion exchange membrane (AEM). Alongside, cation infusion improves the C─C bond formation inducing a favorable micro‐environment for selective C2+ formation. This cation‐infused bilayer ionomer (CIBLI) achieves a high partial current density of ≈284 mA cm−2 toward C2+ products maintaining a stable eCO2R performance for 24 hours (h). This scalable approach of directly deposited ultra‐thin CIBLI offers a minimal conversion energy of 117 GJ/ ton C2+ products with an energy efficiency (EE) of 29% at 350 mA cm−2 current density in one‐step CO2 conversion. [ABSTRACT FROM AUTHOR]

The anion exchange membrane (AEM) suffered from poor mechanical properties and low ionic conductivity in fuel cells. Herein, a series of novel block fluorene‐contained poly(arylene ether ketone)s backbones are synthesized by a tandem one‐pot process and then grafted with alkyl chains to form comb‐shaped structure for preparing AEMs. The one‐pot synthesis of block copolymer avoids the multiple purifications of oligomers. The membranes' structure–property relationship is studied by changing the ratios of hydrophilic and hydrophobic segments. The designed comb‐shaped structures grafted on fluorene‐containing block backbones can widen the space between chains and form clear microphase separation patterns, as determined by atomic force microscope (AFM) and small angle x‐ray scattering (SAXS). Hence, resulting AEMs have a high ionic conductivity (117.4 mS cm−1, 80°C). Meanwhile, they also present low swelling rate (SR) from 12.76% to 18.51% at 30°C, 16.84% to 24.36% at 60°C, and 18.33% to 25.81% at 80°C. In addition, excellent mechanical properties, that is, an elongation at break of 29.63% and a tensile strength of 28.72 MPa, are achieved and showed the promise of as‐fabricated AEMs in fuel cell applications. [ABSTRACT FROM AUTHOR]

Developing anion exchange membranes (AEMs) is an effective way to reduce the cost of water electrolyser systems and fuel cell systems because of the no requirement of platinum-group-metal (PGM) catalysts. However, low conductivity and poor stability are the bottlenecks that constrain its development. In this work, we propose a series of performance enhanced poly (terphenyl-co-fluorene quinuclidinium) (TPFQ) AEMs. The hydroxide conductivity of TPFQ-10 reached 178.5 mS cm−1 at 80 °C. The rigid fluorene group gives the membrane better dimensional stability (swelling ratio: 7.7% in pure water and 1.2% in 10 M NaOH at 80 °C for TPFQ-10). In particular, the membranes exhibit extremely high alkaline stability, with almost no conductivity loss over more than 2000 h in a 10 M NaOH solution. The AEM water electrolysers (AEMWEs) with nickel-alloy foam electrodes shows an excellent current density of 2.32 A cm−2 at 2.0 V. The AEMWEs can work steadily at a current density of 0.5 A cm−2 in 5 M NaOH at 80 °C for more than 500 h, with a low voltage rising rate of 56 μV h−1. • Synthesized a series of performance enhanced poly(terphenyl-co-fluorene quinuclidinium) (TPFQ) AEMs. • The AEMs have a high OH− conductivity (178.5 mS cm−1 at 80 °C), high mechanical properties (60.3 MPa TS) and excellent dimensional stability(swelling ratio: 7.7% in pure water and 1.2% in 10 M NaOH at 80 °C). • The AEMs exhibit extremely high alkaline stability, with almost no conductivity loss over more than 2000 h in a 10 M NaOH solution. • The AEMWE with nickel-alloy foam electrodes shows excellent current density (2.32 A cm−2 at 2.0 V) and high durability. [ABSTRACT FROM AUTHOR]

Developing efficient, low‐cost electrocatalysts for industrial‐level hydrogen production remains a significant challenge. Here lattice‐distorted Ni nanoparticles (NPs) encapsulated within a nitrogen‐doped carbon shell on delignified wood carbon (Ni‐NC@DWC) are constructed through a chitosan‐induced assembly and the pyrolysis process. Experimental and theoretical results indicate that the lattice distortion due to strong metal‐support interactions, boosts electron transfer and reaction intermediate adsorption/desorption, enhancing both the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Interestingly, the active center Ni3+‐O is dynamically cyclically generated during the UOR. When utilized as a self‐standing electrode in an alkaline electrolyte, the Ni‐NC@DWC exhibits low potentials of 24 mV and 1.244 V at 100 mA cm−2 for HER and UOR, respectively. Moreover, the Ni‐NC@DWC achieves an ultrasmall cell voltage of 1.13 V at 100 mA cm−2 for urea‐assisted water splitting and can operate stably over 1000 h. Furthermore, when it is self‐assembled as an anion exchange membrane (AEM) electrolyzer, it requires only 1.62 V at 2000 mA cm−2 for industrial urea‐assisted water splitting and operates stably for 150 h without degradation, confirming that it is highly attractive for economical, sustainable, and scalable hydrogen production. [ABSTRACT FROM AUTHOR]

Poly(arylene piperidinium)s are attractive anion exchange membranes (AEMs) for alkaline membrane fuel cells and water electrolyzers because of their high chemical stability and hydroxide conductivity. Here, ether‐ and fluorine‐free hydroxide conducting poly(quaterphenyl piperidinium) membranes with very similar ion exchange capacity (IEC), but different ratios of meta to para connectivity in the quaterphenyl units, are synthesized and explored. Ionic clustering, water uptake, and the hydroxide conductivity of the AEMs increase gradually with increasing backbone flexibility, i.e., the fraction of meta connectivity. At 80 °C, the AEMs with para,para‐ and meta,meta‐quaterphenyl units, respectively, reach a conductivity of 96 and 178 mS cm−1, respectively, at a water uptake of 37 and 209%, respectively. Alkaline stability evaluations reveal high alkaline stability, increasing with backbone flexibility. Under very harsh conditions, the cationic loss increases with chain stiffness and occurs mainly through Hofmann β‐elimination, but also increasingly via nucleophilic methyl substitution. Copolymerization of quaterphenyls provides properties in between the corresponding homopolymers. In conclusion, it is demonstrated that the configuration of the quaterphenyl monomer can be efficiently tailored to manipulate the chain flexibility of highly alkali‐stable AEMs for control over the water uptake and ionic conductivity in a wide range without changing the ionic content of the membranes. [ABSTRACT FROM AUTHOR]

Poly(ethylene glycol) (PEG) or oligo (ethylene glycol) (OEG) grafted anion exchange membranes (AEMs) exhibit improved ionic conductivity, high alkaline stability, and subsequent boosted AEM fuel cell performance, but too much PEG/OEG side chains may can result in a reduction in the ion exchange capacity (IEC), which can have adverse effects on ion transport. Here, a series of partially PEG‐grafted poly(terphenyl piperidinium) with different side chain length are synthesized using simple postpolymerization modification to produce AEMs with balanced properties. The polar and flexible PEG side chains are responsible for the controlled water uptake and swelling, superior hydroxide conductivity (122 mS cm−1 at 80 °C with an IEC of 1.99 mmol g−1), and enhanced alkaline stability compared to the reference sample without PEG grafts (PTP). More importantly, the performance of AEM fuel cell (AEMFC) with the membrane containing partial PEG side chains surpasses that with PTP membrane, demonstrating a highest peak power density of 1110 mW cm−2 at 80 °C under optimized conditions. This work provides a novel approach to the fabrication of high‐performance AEM materials with balanced properties for alkaline fuel cell application. [ABSTRACT FROM AUTHOR]

Seawater hydrogen production, vital for sustainable energy solutions and freshwater preservation, faces challenges due to seawater complexity and high energy consumption. A strategy to modulate dehydrogenation kinetics of dual‐phase metal nitrides using low‐loaded Pt quantum dots (QDs), achieving stable and energy‐efficient hydrogen generation is introduced. The Pt QDs@Ni3N‐MoN/Ti catalyst displays outstanding bifunctional seawater catalytic performance, enabling efficient hydrogen production and hydrazine degradation in a flow anion exchange membrane water electrolysis (AEMWE) device. Operating at a low voltage of 1.41 V, it achieves 2 A cm−2 for 300 h, circumventing chlorine corrosion and yielding record‐breaking energy equivalent input (2.68 kWh m−3 H2 at 1 A cm−2), a 47.1% reduction compared to traditional methods. Integration with solar and biomass energy facilitates self‐powered hybrid seawater hydrogen production, highlighting its potential applications. This work facilitates energy‐efficient marine resource conversion to green hydrogen and offers viable insights into industrial hazardous pollutant degradation using metal‐nitride electrocatalysts. [ABSTRACT FROM AUTHOR]

This work demonstrates the application of urea-powered paper-based fuel cells (PFCs) with Hydrogen Peroxide (H2O2) as the oxidant to drive a flexible electronic circuit (ring oscillator (RO)), for the first time. Herein, the electrochemical performance of four different PFCs has been studied by employing non-precious electrodes as the anode and cathode. These are the membraneless PFC with (i) Toray carbon paper (CP) (ii) Nickel (Ni)-mesh (iii) Nickel Cobalt nanoparticles supported on reduced Graphene Oxide loaded on the CP (Ni Co@rGo@CP) and (iv) membrane-based PFC with Ni Co@rGo@CP as the electrodes. In each PFC the same electrode is employed on both the sides. A single membraneless-PFC with Ni-Co@rGo@CP as electrodes delivered a peak power density (Pmax) of 55 µW cm−2, maximum current density (Jmax) of 371 µA cm−2 and an open-circuit voltage (OCV) of 0.7 V at 3 M urea. While, a single membrane-based PFC assembled on an anion exchange membrane with Ni-Co@rGo@CP electrodes, delivered a Pmax of ≈70 µW cm−2 and Jmax of ≈500 µA cm−2 at an OCV of 0.7 V with 3 M urea. Subsequently, a stack of two membrane-based PFCs delivered an OCV of ≈1.4 V for 400 s. Finally, this stack is employed as a power source to drive a RO. The measured frequency and peak-to-peak voltage are 37.52 kHz and 1.04 V, respectively. This demonstration opens a window to implement self-contained flexible electronic system using PFCs as the power source with minimal e-waste. [ABSTRACT FROM AUTHOR]

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Metal sulfides are promising alternatives to noble metal electrocatalysts for water‐based hydrogen evolution. Pentlandites, notably, exhibit high activity in acidic environments. To explore their potential in alkaline conditions, pentlandite electrodes are tested in both conventional three‐electrode setups and scaled up to a 12.6 cm2$^{2}$ membrane electrode assembly (MEA). Optimized pentlandites with a stochiometry of M9S8$\left(\text{M}\right)_{9} \left(\text{S}\right)_{8}$, containing Fe, Ni, and Co, show reduced overpotentials for hydrogen evolution with higher Fe and Ni contents. However, a minimum Co content of three equivalents is necessary for peak hydrogen evolution reaction activity with −0.40 V versus reversible hydrogen electrode at −300 mA cm−2$^{- 2}$. Stability assessments via X‐ray photoelectron and Raman spectroscopy reveal minor surface changes for Fe and Ni species but significant leaching of cobalt from Co4.5$_{4.5}$Ni4.5$_{4.5}$S8$_{8}$ surfaces postelectrolysis. Selected pentlandite catalysts are integrated into MEAs, with Fe4Co3Ni2S8$\left(\text{Fe}\right)_{4} \left(\text{Co}\right)_{3} \left(\text{Ni}\right)_{2} \left(\text{S}\right)_{8}$ achieving 1 A cm−2$^{- 2}$ at 2.2 V with minimal potential decay of 50 μV h−1$^{- 1}$ alongside a La0.8$_{0.8}$Sr0.2$_{0.2}$CoO3$_{3}$ anode. These findings underscore the suitability of pentlandite catalysts for water splitting at industrial scales under alkaline conditions. [ABSTRACT FROM AUTHOR]

Seawater hydrogen production, vital for sustainable energy solutions and freshwater preservation, faces challenges due to seawater complexity and high energy consumption. A strategy to modulate dehydrogenation kinetics of dual‐phase metal nitrides using low‐loaded Pt quantum dots (QDs), achieving stable and energy‐efficient hydrogen generation is introduced. The Pt QDs@Ni3N‐MoN/Ti catalyst displays outstanding bifunctional seawater catalytic performance, enabling efficient hydrogen production and hydrazine degradation in a flow anion exchange membrane water electrolysis (AEMWE) device. Operating at a low voltage of 1.41 V, it achieves 2 A cm−2 for 300 h, circumventing chlorine corrosion and yielding record‐breaking energy equivalent input (2.68 kWh m−3 H2 at 1 A cm−2), a 47.1% reduction compared to traditional methods. Integration with solar and biomass energy facilitates self‐powered hybrid seawater hydrogen production, highlighting its potential applications. This work facilitates energy‐efficient marine resource conversion to green hydrogen and offers viable insights into industrial hazardous pollutant degradation using metal‐nitride electrocatalysts. [ABSTRACT FROM AUTHOR]

Alkaline‐stable, highly conductive anion exchange membranes (AEMs) are attentively expected solid polymer electrolytes that contribute to achieving high performance and durability for anion exchange membrane water electrolyzers (AEMWEs). The technical challenges of AEMs mainly stem from the degradation of the polymer backbones, side chains, and anchoring cationic groups. Herein, new and stable AEMs (QTAF) are designed using 3,3′′‐dichloro‐2′,5′‐bis(trifluoromethyl)‐1,1′:4′,1′′‐terphenyl (TFP) monomers as the hydrophobic component incorporated into the polyphenylene backbone and 3,3′‐(2,7‐dichloro‐9H‐fluorene‐9,9‐diyl)bis(N,N‐dimethylpropane‐1‐amine) (AF) monomers as the hydrophilic component. After tuning the copolymer composition, the highest hydroxide ion conductivity (168.7 mS cm−1 at 80 °C) is achieved with the QTAF‐3.0 membrane. The QTAF‐3.0 membrane survives in harsh alkaline conditions (8 M KOH solution, 80 °C), with high conductivity (75.8 mS cm−1) after 810 h. A water electrolysis cell with QTAF‐3.0 membrane and non‐noble Ni0.8Co0.2O anode catalyst operates stably at a constant current density (1.0 A cm−2) for 1000 h with a negligible voltage increase rate of 1.1 µV h−1 after the initial voltage increase. The water electrolysis performance of the post‐tested QTAF‐3.0 cell is 1.83 V, only a 6.4% increase from the initial performance at 2.0 A cm−2, suggesting the high potential of the QTAF‐3.0 membrane for practical AEMWE applications. [ABSTRACT FROM AUTHOR]

Asymmetric coordination has emerged as a promising approach to enhance the oxygen evolution reaction (OER) activity, yet achieving a controlled synthesis of asymmetric structures to comprehensively understand the structure‐activity relationship remains challenging. In this study, a facile and effective symmetry‐breaking strategy is reported for tailoring the asymmetric MO5S1‐type metal–organic frameworks (MOFs) catalyst, establishing the correlation between the sulfur (S)‐mediated electron rearrangement and the adsorption/desorption dynamics of oxygen‐related intermediates in OER. Experimental and theoretical calculations reveal that a well‐designed asymmetric structure can effectively lower the d‐band center, optimizing the adsorption behavior of OH* and significantly decreasing the reaction energy barrier for the rate‐determining step (OH* → O*) with enhanced O–H bond cleavage process. The S‐NiFe‐MOF/CFP catalyst demonstrates a remarkable OER performance in an alkaline electrolyte environment. More importantly, the self‐assembled anion exchange membrane water electrolysis cell showcases a low voltage of 1.84 V to deliver the current density of 1 A cm−2, maintaining long‐term stability for over 100 h. This study unveils a precise asymmetric synthesis strategy employing S, highlighting the critical role of manipulating electron redistribution through asymmetric coordination to promote catalytic activity and develop advanced MOF‐based catalysts. [ABSTRACT FROM AUTHOR]

In‐depth comprehension and improvement of the sluggish hydrogen evolution kinetics in alkaline media is highly important to enhance the activity and durability of anion exchange membrane water electrolysis (AEMWE) for green hydrogen production. Herein, a hydrogen atom‐terminated core–shell PdH@Ru nanobamboos (NBs) is developed by the synergetic strategy of epitaxial growth and in situ DMF hydrogenation. The synthesized PdH@Ru NBs demonstrate exceptional activity for hydrogen evolution reaction (HER) in alkaline media, requiring only a 14 mV overpotential at the 10 mA cm−2, surpassing those of commercial Pt/C (35 mV) and H‐free Pd@Ru NBs (37 mV). Furthermore, an AEMWE device using PdH@Ru NBs as the cathode also achieves the current density of 1000 mA cm−2 at ≈1.80 V in 1.0 m KOH at 60 °C, with continuous operation for 50 h. The operando spectroscopic analysis and density functional theory calculations suggest that hydrogen insertion into the Pd@Ru NBs induces tensile strain on the Ru surface layer, altering the Pd/Ru electronic structure and weakening H adsorption, thereby enhancing the HER efficiency. The bamboo‐like hollow structure features numerous active sites, which contribute to the optimization of electron/mass diffusion in the alkaline electrolyte. This work provides a potential high‐efficiency cathodic electrocatalyst for industrial hydrogen production. [ABSTRACT FROM AUTHOR]

Transition metal coordination polymers (TM‐CP) are promising inexpensive and flexible electrocatalysts for oxygen evolution reaction in water electrolysis, while their facile synthesis and controllable regulation remain challenging. Here we report an anodic oxidation‐electrodeposition strategy for the growth of TM‐CP (TM=Fe, Co, Ni, Cr, Mn; CP=polyaniline, polypyrrole) films on a variety of metal substrates that act as both catalyst supports and metal ion sources. An exemplified bimetallic NiFe‐polypyrrole (NiFe‐PPy) features superior mechanical stability in friction and exhibits high activity with long‐term durability in alkaline seawater (over 2000 h) and anion exchange membrane electrolyzer devices at current density of 500 mA cm−2. Spectroscopic and microscopic analysis unravels the configurations with atomically distributed metal sites induced by d‐π conjugation, which transforms into a mosaic structure with NiFe (oxy)hydroxides embedded in PPy matrix during oxygen evolution. The superior catalytic performance is ascribed to the anchoring effect of PPy that inhibits metal dissolution, the strong substrate‐to‐catalyst interaction that ensures good adhesion, and the Fe/Ni−N coordination that modulates the electronic structures to facilitate the deprotonation of *OOH intermediate. This work provides a general strategy and mechanistic insight into building robust inorganic/polymer composite electrodes for oxygen electrocatalysis. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) from seawater electrolysis still faces challenges of low reactivity and chloride ions poison at the active sites, leading to reduced efficiency and stability of electrocatalysts. This study presents edge dislocation strategy aimed at inducing lattice strain in ferric oxide through Mo doping, consequently regulating the catalyst's band structure. Through in situ characterizations and DFT analysis, it is confirmed that lattice strain effectively modulates the band structure, intensifies the hybridization between Mo(d)‐Fe(d)‐O(p) orbitals, thereby accelerating the charge transfer rate of HER. Furthermore, band structure modulated by lattice strain enhances water adsorption capacity, reduces the adsorption energy of Cl−, and optimizes the hydrogen adsorption‐free energy (ΔGH*) for HER. Benefiting from above, the optimized 2%‐Mo‐Fe2O3 catalyst demonstrates HER activity and stability in alkaline seawater electrolysis comparable to that of commercial Pt/C. Additionally, the assembled electrolytic cell utilizing an anion exchange membrane (AEM) maintains long‐term stability for >100 h at 500 mA cm−2, showcasing a sustained catalytic effect. [ABSTRACT FROM AUTHOR]

Although anion exchange membrane water electrolyzer (AEMWE) is an emerging device in the green hydrogen production industry, the use of alkaline electrolyte tackles the practicality due to the issues of lowering system efficiency and environmental impacts. State‐of‐the‐art technology using pure water as an electrolyte is advancing to overcome the current challenges of AEMWE. In particular, the development of this technology requires a comprehensive evaluation of techno‐economic aspects, aiming to balance innovation with cost considerations. This involves the critical development of advanced catalysts, membranes, and devices designed for efficiency, as well as assessing their economic viability amidst prevailing technological challenges. This review delves into the timely technical challenges of developing pure water‐fed AEMWE, highlights current progress and research prospects, and suggests opportunities for advancing AEMWE technology. This review also emphasizes the importance of advanced characterization techniques for effective analysis and evaluation in this context. [ABSTRACT FROM AUTHOR]

Relative to suppressed conductometric anion exchange chromatography, conductometric ion exclusion chromatography (IEC) is much less popular. Poor limit of detection and manual preparation of eluent are primarily responsible for this. We describe an electrodialytic phosphoric eluent generator for the online production of phosphoric acid eluent at a concentration exceeding 35 mM. It is a sandwiched configuration consisting of three channels isolated by stacked anion exchange membranes and a bipolar membrane plus stacked anion exchange membrane. Such a unique configuration ensures the production of gas‐free eluent, obviating the need for a gas removal device. The resulting eluent concentration is controlled by varying the current. Coupled with an ultraviolet absorbance detector, a 0.04–16.67 mg/L limit of detection for model organic acids was achieved by IEC equipped with an electrodialytic phosphoric eluent generator. [ABSTRACT FROM AUTHOR]

Green hydrogen (H2) is an essential component of global plans to reduce carbon emissions from hard‐to‐abate industries and heavy transport. However, challenges remain in the highly efficient H2 production from water electrolysis powered by renewable energies. The sluggish oxygen evolution restrains the H2 production from water splitting. Rational electrocatalyst designs for highly efficient H2 production and oxygen evolution are pivotal for water electrolysis. With the development of high‐performance electrolyzers, the scale‐up of H2 production to an industrial‐level related activity can be achieved. This review summarizes recent advances in water electrolysis such as the proton exchange membrane water electrolyzer (PEMWE) and anion exchange membrane water electrolyzer (AEMWE). The critical challenges for PEMWE and AEMWE are the high cost of noble‐metal catalysts and their durability, respectively. This review highlights the anode and cathode designs for improving the catalytic performance of electrocatalysts, the electrolyte and membrane engineering for membrane electrode assembly (MEA) optimizations, and stack systems for the most promising electrolyzers in water electrolysis. Besides, the advantages of integrating water electrolyzers, fuel cells (FC), and regenerative fuel cells (RFC) into the hydrogen ecosystem are introduced. Finally, the perspective of electrolyzer designs with superior performance is presented. [ABSTRACT FROM AUTHOR]

Anion exchange membrane water electrolysis (AEMWE) has gained attention as an attractive alternative to alkaline and proton exchange membrane water electrolysis (PEMWE) due to its high efficiency and low hydrogen unit cost. However, the long‐term durability of AEMWE is ≈10 times lower than that of PEMWE, which typically operates for 40 000 h. Here, a new design strategy is presented for aryl ether‐free PFPBPF‐QA anion exchange membranes with interstitial alkyl chains in the conducting groups and polymer backbone. The rationally designed PFPBPF‐4‐QA, with a suitable ion exchange capacity, shows high ionic conductivity, mechanical properties, alkaline stability, and stronger membrane‐ionomer contact properties at the catalyst layers. A single AEMWE cell using PFPBPF‐4‐QA demonstrated a voltage decay rate of 2 mV kh−1 at 1.0 A cm−2, which is significantly lower than that reported for AEMWEs and Nafion‐based PEMWEs. Additionally, a large‐sized 1‐cell AEMWE stack utilizing PFPBPF‐4‐QA with an active area of 63.6 cm2 achieved an energy conversion efficiency of 80.2% and a voltage decay rate of 1.5 mV kh−1 for 2 000 h, with over 90% of the initial efficiency maintained for over 49 095 h based on an exponential fitting calculation. [ABSTRACT FROM AUTHOR]

Vanadium redox flow batteries (VRFBs) depend on the separator membrane for their efficiency and cycle life. Herein, two amphoteric ion exchange membranes are synthesized, based on sulfonic acid group‐grafted poly(p‐terphenyl piperidinium), for VRFBs. Using ether‐free poly(p‐terphenyl piperidine) (PTP) as the polymer matrix, and sodium 2‐bromoethanesulphonate (ES) and 1,4‐butane sultone (BS) as grafting agents, We achieve quaternization of PTP through an environmentally friendly process without alkaline catalysts. PTP‐ES and PTP‐BS membranes exhibit low area resistance, high H+ permeability, and significantly reduced vanadium ion permeability, leading to exceptional ion selectivity, which is 3.06 × 106 S min cm−3 and 4.34 × 106 S min cm−3, respectively, three orders of magnitude higher than that of Nafion115 (0.27 × 104 S min cm−3). The VRFB with PTP‐BS achieves a self‐discharge duration of 190 h, compared to 86 h for Nafion 115. Additionally, under current densities of 40—160 mA cm−2, PTP‐BS shows coulombic efficiencies of 98.1–99.1% and energy efficiencies of 92.0–82.1%, outperforming Nafion 115. The VRFB with PTP‐BS also demonstrates excellent cycle stability and discharge capacity retention over 300 cycles at 100 mA cm−2. Therefore, the amphoteric PTP‐BS membrane shows remarkable performance, offering significant potential for VRFB applications. [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]

Hydrogen crossover in water electrolyzer systems equipped with ion exchange membranes (IEM) poses significant safety risks and reduces overall process efficiency. This communication identifies and addresses two critical errors in current hydrogen crossover literature: inaccurate measurement methods and the inappropriate use of permeability (e.g., barrer) to quantify hydrogen crossover. Accurate evaluation of hydrogen crossover through an IEM can be challenging because it is a two-phase material fully hydrated in liquid water. We propose a standardized protocol for accurately measuring hydrogen crossover in fully hydrated IEMs and emphasize the necessity of using flux (e.g., mole∙m−2∙s−1) instead of permeability (e.g., barrer) dimension. The obtained data reveal that normalizing hydrogen crossover by transmembrane pressure and membrane thickness can result in significant errors, with relative errors reaching up to 25%. When applied to the actual electrolysis operation, using the permeability data to predict hydrogen crossover at a current density of 0.4 A cm−2 results in 47% error, with the actual system reaching the lower explosion limit (LEL) while the predicted value does not. Additionally, hydrogen crossover data provides insights into the internal ion channel morphology of IEMs. This communication article intends to convey the current existing safety hazards to the hydrogen research community with a detailed transport models and validation. [Display omitted] • Two fatal errors when describing the hydrogen crossover phenomenon were assessed. • Hydrated ion exchange membrane behaves as a two-phase material. • Inappropriate use of the permeability dimension (barrer) has been evaluated. • Unstandardized measurement methods increase the process safety risk. • Appropriate solutions have been suggested for each hazardous practice. [ABSTRACT FROM AUTHOR]

The power output of reverse electrodialysis (RED), an important renewable energy technology, can be improved using high-salinity feed solutions. Herein, a RED stack of ultrathin ion exchange membranes was operated continuously for 10 days using reverse osmosis brine (~0.9 M NaClequivalent) and underground water (~0.01 M NaClequivalent). The net power and net energy efficiency were initially 1.8 W m−2cell pair and 40.8%, respectively, and then decreased gradually, as did the generated current and stack resistance. This deterioration was caused not by conventional membrane fouling but by trapped water inside the polymer matrix of the anion exchange membrane, especially near the cathode. The high salinity gradient and ultrathin membranes caused a flux imbalance between co-ion transport and osmotic water permeation. Further, bulk mass transfer was enhanced inside the RED stack to maintain electroneutrality. Therefore, combinations of membranes with high water permeability and permselectivity may be required to achieve stable RED operation. [ABSTRACT FROM AUTHOR]

Ion exchange membranes (IEMs) play a critical role in aqueous organic redox flow batteries (AORFBs). Traditional IEMs that feature microphase‐separated microstructures are well‐developed and easily available but suffer from the conductivity/selectivity tradeoff. The emerging charged microporous polymer membranes show the potential to overcome this tradeoff, yet their commercialization is still hindered by tedious syntheses and demanding conditions. We herein combine the advantages of these two types of membrane materials via simple in situ hypercrosslinking of conventional IEMs into microporous ones. Such a concept is exemplified by the very cheap commercial quaternized polyphenylene oxide membrane. The hypercrosslinking treatment turns poor‐performance membranes into high‐performance ones, as demonstrated by the above 10‐fold selectivity enhancement and much‐improved conductivities that more than doubled. This turn is also confirmed by the effective and stable pH‐neutral AORFB with decreased membrane resistance and at least an order of magnitude lower capacity loss rate. This battery shows advantages over other reported AORFBs in terms of a low capacity loss rate (0.0017 % per cycle) at high current density. This work provides an economically feasible method for designing AORFB‐oriented membranes with microporosity. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) is an appealing method for carbon utilization. Alkaline CO2 electrolyzers exhibit high CO2RR activity, low full‐cell voltages, and cost‐effectiveness. However, the issue of CO2 loss caused by (bi)carbonate formation leads to excessive energy consumption, rendering the process economically impractical. In this study, we propose a trilayer polymer electrolyte (TPE) comprising a perforated anion exchange membrane (PAEM) and a bipolar membrane (BPM) to facilitate alkaline CO2RR. This TPE enables the coexistence of high alkalinity near the catalyst surface and the H+ flux at the interface between the PAEM and the cation exchange layer (CEL) of the BPM, conditions favoring both CO2 reduction to multicarbon products and (bi)carbonate removal in KOH‐fed membrane electrode assembly (MEA) reactors. As a result, we achieve a Faradaic efficiency (FE) of approximately 46 % for C2H4, corresponding to a C2+ FE of 64 % at 260 mA cm−2, with a CO2‐to‐C2H4 single‐pass conversion (SPC) of approximately 32 % at 140 mA cm−2—nearly 1.3 times the limiting SPC in conventional AEM‐MEA electrolyzers. Furthermore, coupling CO2 reduction with formaldehyde oxidation reaction (FOR) in the TPE‐MEA electrolyzer reduces the full‐cell voltage to 2.3 V at 100 mA cm−2 without compromising the C2H4 FE. [ABSTRACT FROM AUTHOR]

Environmental friendliness and low‐cost zinc‐air batteries for flexible rechargeable applications have great potential in the field of flexible electronics and smart wearables owing to high energy density and long service life. However, the current technology of flexible rechargeable zinc‐air batteries to meet the commercialization needs still facing enormous challenges due to the poor adaptability of each flexible component of the zinc‐air batteries. This review focused on the latest progress over the past 5 years in designing and fabricating flexible self‐standing air electrodes, flexible electrolytes and zinc electrodes of flexible Zn‐air batteries, meanwhile the basic working principle of each component of flexible rechargeable zinc‐air batteries and battery structures optimization are also described. Finally, challenges and prospects for the future development of flexible rechargeable zinc‐air batteries are discussed. This work is intended to provide insights and general guidance for future exploration of the design and fabrication on high‐performance flexible rechargeable zinc‐air batteries. [ABSTRACT FROM AUTHOR]

Recognizing the essential factor governing interfacial hydrogen/oxygen evolution reactions (HER/OER) is central to electrocatalytic water‐splitting. Traditional strategies aiming at enhancing electrocatalytic activities have mainly focused on manipulating active site valencies or coordination environments. Herein, the role of interfacial adsorption is probed and modulated by the topological construct of the electrocatalyst, a frequently underestimated non‐Faradaic mechanism in the dynamics of electrocatalysis. The engineered Co0.75Fe0.25P nanorods, anchored with FeOx clusters, manifest a marked amplification of the surface electric field, thus delivering a substantially improved bifunctional electrocatalytic performance. In alkaline water splitting anion exchange membrane (AEM) electrolyzer, the current density of 1.0 A cm−2 can be achieved at a cell voltage of only 1.73 V for the FeOx@Co0.75Fe0.25P|| FeOx@Co0.75Fe0.25P pairs for 120 h of continuous operation at 1.0 A cm−2. Detailed investigations of electronic structures, combined with valence state and coordination geometry assessments, reveal that the enhancement of catalytic behavior in FeOx@Co0.75Fe0.25P is chiefly attributed to the strengthened adsorptive interactions prompted by the intensified electric field at the surface. The congruent effects observed in FeOx‐cluster‐decorated Co0.75Fe0.25P nanosheets underscore the ubiquity of this effect. The results put forth a compelling proposition for leveraging interfacial charge densification via deliberate cluster supplementation. [ABSTRACT FROM AUTHOR]

The reconstructed surface structure of Co‐based spinel oxides serves as the active site for oxygen evolution reaction (OER). However, the structural complexity of spinel oxides and surface dynamics during the OER hinder the understanding of the reconstruction mechanism and electronic structure of the active site. In this study, spinel Co3O4@(CoFeV)3O4 nanocube (CoFeV) is reported, a (001) facet‐defined spinel oxide comprising Co, Fe, and V deposited on the Co3O4 nanocube template to exclude facet‐dependent factors. Introducing highly dissoluble V cations accelerates the reconstruction process to enhance the electrocatalytic activity. CoFeV exhibited enhanced electrocatalytic activity (266 mV at 10 mA cm−2 in 1 M KOH) and durability (maintained stable electrocatalytic activity during a 200 h chronopotentiometry (CP) test at 100 mA cm−2) with significantly enlarged electrochemically active surface area (ECSA). The experimental and theoretical results demonstrated that V dissolution during catalysis induced oxygen vacancies, accelerating the surface reconstruction to highly active oxyhydroxide. Consequently, the anion exchange membrane water electrolyzer (AEMWE) of CoFeV as the anode exhibited a remarkable performance of 6.19 A cm−2 at 2.0 Vcell in 1 M KOH and robust durability for 96 h at a constant current density of 500 mA cm−2. [ABSTRACT FROM AUTHOR]

The nitrogen‐rich molybdenum nitrides (N/Mo > 1) are promising for water electrolysis due to their increased activity and antioxidant ability. However, a higher temperature is needed in the usual synthesis for introducing more N, leading to the formation of large particles and the difficulty in controlling the morphology, thus limiting their catalytic performance. Here, a new strategy is reported based on the synergy of internal/external N sources (INS and ENS) toward Mo5N6‐based catalysts at a decreased temperature of 450 °C. The PMo12 clusters and Ni2+ (Co2+) are first combined with 2‐methylimidazole/melamine (INS) to give a flower‐like assembly. The subsequent pyrolysis under NH3 flow (ENS) gives the flowers composed of small Mo5N6/Ni (Co) heterojunctional particles that can expose more surface sites with an optimized electronic structure. The Mo5N6/Ni exhibits good HER activity close to Pt/C, and Mo5N6/Co shows superior OER performance to IrO2. The Mo5N6/Ni||Mo5N6/Co cell drives overall water splitting (OWS) at a low voltage of 1.397/1.74 V to achieve a current density of 10/100 mA cm−2 in the 1.0 M KOH. An anion exchange membrane water electrolyzer (AEMWE) based on the catalysts can achieve a current density of 450 mA cm−2 at 1.8 V with a long‐term stability of 120 h. [ABSTRACT FROM AUTHOR]

High electrochemical and durability anion exchange membranes (AEMs) are a vital material for Flexible zinc‐air batteries (F‐ZAB) and AEM water electrolysis (AEMWE) to achieve green economy and environmental protection. However, the existing AEMs possess the disadvantages of a complicated preparation process, poor homogeneity, and unsatisfactory electrochemical performance. Here, a novel alkaline exchange membrane is synthesized using bacterial cellulose (BC) as the matrix, incorporating constrained in situ Poly (diallyldimethylammonium chloride) (PDDA) polymerization and double chemical cross‐linking techniques. By adjusting the microstructure, a unique long‐range order and dense internal structure to address the issue of loose bonding between PDDA and BC is established and achieve the purpose of rapid OH− conduction. The membranes exhibit excellent application properties, with excellent ionic conductivity (145.12 mS cm−1) and superb mechanical strength (73.26 MPa). Consequently, the membrane is assembled into the F‐ZAB, and the unprecedented power density of 258.7 mW cm−2 can be achieved at room temperature. Moreover, the membrane also can reach 3.0 A cm−2 at 2.3 V, indicating good prospects in the field of water electrolysis in 6 m KOH. The approach paves a new path for manufacturing AEMs for green energy and environmental applications. [ABSTRACT FROM AUTHOR]

Low hydroxide conductivity and insufficient alkaline stability are the main problems currently facing anion exchange membranes (AEMs). Conventional quaternary ammonium groups have limited resistance to attack by hydroxide roots. In this paper, quaternary ammonium-type (Cn-PFCO (n = 2, 5)) perfluoroanion exchange polymers with carbonyl side chains were synthesized. The C5–PFCO exhibited an impressive conductivity of 113.4 mS cm−1 at 80 °C, and remarkably, it retained 86.87% of its initial conductivity even after 15 days of immersion in a 1 M KOH aqueous solution. This excellent alkali resistance is due to the generation of intermediate oxygen anions from OH− and carbonyl groups through a reversible reaction. These anions effectively reduce the likelihood of S N 2 attack by diminishing the electrostatic potential of the QA groups from Density Functional Theory (DFT) calculations. The electrostatic potential of C2–PFCO is 6.28 eV, while it decreases to 2.69 eV after the formation of intermediate anions. Furthermore, we also used the prepared AEM for pure water electrolysis to explore its performance. The electrochemical performance of AEMWE exhibited remarkable results when supplied with pure water, demonstrating an impressive current density of 262 mA cm−2 at 1.9 V. This study introduces a novel strategy for concurrently enhancing hydroxide conductivity and alkali resistance in AEMs by analyzing the potential for further improvement in AEMs' alkali resistance. [Display omitted] • The AEM with tetrafluoroethylene backbone maintains excellent physicochemical stability. • The presence of carbonyl groups enables sustainable mitigation of hydroxide attacks. • DFT calculations revealed that the ESP of the Cn-PFCO membrane was notably lower (2.69 eV). • The prepared AEM demonstrated excellent alkaline stability in long-term testing. [ABSTRACT FROM AUTHOR]

In this study, the microstructure of carbon fiber paper is modified through H 3 PO 4 etching to enhance the electrolyzer performance. The effects of different H 3 PO 4 concentrations and different soaking times on the hydrogen evolution reaction are firstly investigated. The electrochemical test results show that the best performance of etched electrodes is achieved at a H 3 PO 4 concentration of 1 M and a soaking time of 12 h, with a significant reduction in charge transfer resistance and overpotential. Subsequently, to explore the change mechanism in electrochemical properties, the microstructure of the carbon paper is investigated using Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP) tests, which show uniformly distributed micropores appear on the surface of the carbon fibers after etching, and the porosity increases from 0.74 to 0.8. Brunauer-Emmett-Teller (BET) tests show that the specific surface area of the carbon paper increases from 0.72 m2/g to 4.06 m2/g, which effectively increases the interfacial contact area between the catalyst layer and the liquid gas diffusion layer. Furthermore, a 3D multi-physics model is established to further elucidate the impact mechanism of changes in porosity, conductivity, and active specific surface area on the performance of anion exchange membrane electrolyzer, with changes in active specific surface area having the greatest effect. • Microporous structure of the carbon paper LGDL is modified by etching. • The etching method effectively improves the performance of AEMEL. • The increase in specific surface area and porosity greatly reduces the resistance. • Numerical modeling to analyze the impact of microscopic parameters on AEMEL. • LGDL with high specific surface area has a positive effect on AEMEL's development. [ABSTRACT FROM AUTHOR]

This review covers the methods of hydrogen production through water electrolysis, encountered problems, used catalysts, methods of preparing these catalysts, and especially the method of electrode modification using the electrophoretic deposition technique. The methods of hydrogen production mechanism, electrode and electrocatalyst structures, and electrode modification techniques are classified based on types of the electrolyzers namely Alkaline Water Electrolysis (AEL), Anion Exchange Membrane (AEM) Water Electrolysis, Proton Exchange Membrane Electrolysis (PEMEL) and Solid Oxide Electrolysis (SOEL). The mechanisms of hydrogen evolution and oxygen evolution reactions, which are crucial in hydrogen production, have been provided in all types of electrolyzers. The parameters influencing these reactions on the anode and cathode electrodes have been discussed. This review summarizes and compares important parameters that show the catalyst's performance in detail. The fundamental principles of the electrophoretic deposition technique have been explained, and examples of electrocatalysts prepared using this technique have been provided. • Green hydrogen production technologies are introduced based on water electrolyzers. • Electrocatalysts used in water electrolyzers are discussed. • Enhanced electrode modification techniques are introduced and compared. • Electrophoretic deposition of catalysts on the electrodes of water electrolyzers are reviewed in detail. [ABSTRACT FROM AUTHOR]

Perovskite materials that aren't stable during the oxygen evolution reaction (OER) are unsuitable for anion‐exchange membrane water electrolyzers (AEMWE). But through manipulating their electronic structures, their performance can further increase. Among the first‐row transition metals, nickel and iron are widely recognized as prominent electrocatalysts; thus, the researchers are looking into how combining them can improve the OER. Recent research has actively explored the design and study of heterostructures in this field, showcasing the dynamic exploration of innovative catalyst configurations. In this study, a heterostructure is used to manipulate the electronic structure of LaNiO3 (LNO) to improve both OER properties and durability. Through adsorbing iron onto the LNO (LNO@Fe) as γ iron oxyhydroxide (γ‐FeOOH), the binding energy of nickel in the LNO exhibited negative shifts, inferring nickel movement toward the metallic state. Consequently, the electrochemical properties of LNO@Fe are further improved. LNO@Fe showed excellent performance (1.98 A cm−2, 1 m KOH, 50 °C at 1.85 V) with 84.1% cell efficiency in AEMWE single cells, demonstrating great improvement relative to LNO. The degradation for the 850 h durability analysis of LNO@Fe is ≈68 mV kh−1, which is ≈58 times less than that of LNO. [ABSTRACT FROM AUTHOR]

Salinity gradient energy presents a promising opportunity for renewable energy, gaining significant interest in the sustainable power sector. This article presents an overview of the application of ion exchange membranes and reverse electrodialysis techniques to harness energy from salinity gradients in seawater, employing anthropomorphic terminology to enhance understanding. The main focus lies in the utilization of ion exchange membrane technology for power generation, with a particular emphasis on its current implementation status and underlying operational principles. The research aims to enhance readers' comprehension of salinity gradient energy in seawater and promote awareness of "energy security" through the use of descriptive language. [ABSTRACT FROM AUTHOR]

In this work, a poly (vinylidene fluoride) (PVDF) and cellulose acetate (CA) blend membrane is developed using the solution casting method for a direct methanol fuel cell (DMFC). The CA addition in PVDF polymer reduces the dense structure of the polymer and creates a porous surface by increasing the amorphous region that is confirmed by surface morphology and crystallinity examination tests. The high glass transition temperature of CA boosts the protection from the melting of PVDF membrane and increases the thermal shrinkage that reduces the probability of a short circuit. PVDF and CA with abundant hydroxyl groups and carboxylic groups enhance the water uptake, also the hydrogen bonding in between them promotes the mechanical strength and develops a tortuous structure that allows protons to pass through them and block the methanol crossover. The 60% PVDF and 40% CA blend membrane shows an ion exchange capacity value of 0.91 and a methanol permeability value of 4.21 × 10–7 cm2 s−1, which is lower than that of the conventional Nafion 117 membrane (19.5 × 10–7 cm2 s−1). A direct methanol fuel cell with this membrane represents a power density value of 16.5 mW cm−2 with a voltage and current density values of 0.178 V and 165 mA cm−2 at 1 M methanol concentration and room temperature. Moreover, it shows a 70% voltage retention after 20 h of testing of the cell at room temperature that is superior to that of the commercial Nafion 117 membrane (48% voltage retention). [ABSTRACT FROM AUTHOR]

The use of green hydrogen as a high-energy fuel of the future may be an opportunity to balance the unstable energy system, which still relies on renewable energy sources. This work is a comprehensive review of recent advancements in green hydrogen production. This review outlines the current energy consumption trends. It presents the tasks and challenges of the hydrogen economy towards green hydrogen, including production, purification, transportation, storage, and conversion into electricity. This work presents the main types of water electrolyzers: alkaline electrolyzers, proton exchange membrane electrolyzers, solid oxide electrolyzers, and anion exchange membrane electrolyzers. Despite the higher production costs of green hydrogen compared to grey hydrogen, this review suggests that as renewable energy technologies become cheaper and more efficient, the cost of green hydrogen is expected to decrease. The review highlights the need for cost-effective and efficient electrode materials for large-scale applications. It concludes by comparing the operating parameters and cost considerations of the different electrolyzer technologies. It sets targets for 2050 to improve the efficiency, durability, and scalability of electrolyzers. The review underscores the importance of ongoing research and development to address the limitations of current electrolyzer technology and to make green hydrogen production more competitive with fossil fuels. [ABSTRACT FROM AUTHOR]

Ion exchange membranes were fabricated using a phase inversion technique based on polyvinyl chloride nanocomposites. Subsequently, electrodialysis membranes were modified by the addition of [SiO2-co-Ag] nanoparticles using magnetron sputtering. The impact of varying concentrations of [SiO2-co-Ag] nanoparticles on the performance of mixed-matrix poly (vinyl chloride)-based nanoparticle cation exchange membranes was studied. Various techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning optical microscopy (SOM) confirmed the presence of nanoparticles in the structure of membranes. The SEM images showed that the addition of SiO2-co-Ag nanoparticles resulted in a more compact structure for the modified membranes. The SOM images show that the fabricated membranes had a uniform surface and uniform distribution of SiO2-Ag in the membrane matrix. The AFM images revealed that the modified membranes had a rough surface at high additive concentrations (4.0% wt.) and cross-sectional SEM images confirmed that the addition of nanoparticles created cracks and cavities in the membrane structure. The hydrophilicity of silica and silver nanoparticles increased the surface hydrophilicity of the modified membranes. The membrane potential, permselectivity, and transport number showed fluctuations, decreasing initially with the use of SiO2-co-Ag nanoparticles up to a concentration of 1.0% wt and then increasing with an increase in the concentration of nanoparticles to 2.0% wt before declining again for a concentration of 4.0% wt. The flux and ionic permeability were promoted by the addition of SiO2-co-Ag up to 1.0% wt, but after that, they showed a decreasing trend with an increase in the concentration of nanoparticles. The areal electrical resistance of the prepared membrane dramatically declined with an increase in the concentration of SiO2-Ag. Importantly, the application of these membranes was in electrodialysis, and the use of also enhanced the mechanical resistance of the membranes. Furthermore, the fabricated membranes exhibited a good ability to remove E. coli from water. Notably, the modified membrane with a 1.0% wt concentration of SiO2-co-Ag nanoparticles demonstrated greater performance in removing E. coli. [ABSTRACT FROM AUTHOR]

The technological progress and consumerism trend stimulate electric and electronic equipment replacing, inducing the generation of huge amounts of wastes, many of them containing dangerous (but valuable) waste printed circuit boards (WPCBs). A promising technology for their recycling is based on the electrochemically regenerable Br-/Br2 leaching system, for which the raw materials can be produced and recycled by electrochemical ways. In this context, the present work presents our research concerning the feasibility to produce by electrodialysis, on-site, HBr and KOH, which are required for the electro-hydrometallurgical recovery of metals from WPCBs. For this purpose, a four-compartment filter-press electrochemical reactor, divided by two cation and one anion exchange membranes, was used. The obtained results demonstrate that the proposed process can produce, at a current density of 4 kA/m², target solutions with concentrations over the required value (of 0.5 M), with average current efficiencies over 73% and 82%, and average specific energy consumptions around 40 and 25 kWh/kg for HBr and KOH, respectively. Moreover, several preliminary measurements performed simultaneously with the electrodialysis tests revealed that, by acquiring rigorous temperature data, the concentrations of the target solutions can be easily and rapidly evaluated and monitored on-line using simple electrochemical sensors for pH and conductivity, but more accurate and exhaustive calibration data is required. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has been extensively studied for fabricating ion exchange membranes. This material is of interest due to its surface‐governed charge which, combined with the interlayer distance between the GO flakes stack, offers ion selectivity. However, obtaining high‐performing membranes with high ion selectivity and low ionic resistance remains challenging. To address this issue, Al(OH)4− anions are incorporated into graphene oxide membranes to increase their spontaneous negative surface charge. The anions are successfully formed and encapsulated through a reaction with the alumina support under alkaline conditions during the membrane fabrication. A modeling of the system proves the anchoring of the Al(OH)4− anions within the GO matrix. The incorporation of these anions significantly improves the permselectivity and reduces the ionic resistance, reaching approximately 95% and 2 Ω cm2, respectively. The GO‐modified membranes also present mono‐valent selectivity, which can boost reverse electrodialysis power densities. [ABSTRACT FROM AUTHOR]

Anion exchange membrane fuel cell (AEMFC) technology is attracting intensive attention, due to its great potential by using non‐precious‐metal catalysts (NPMCs) in the cathode and cheap bipolar plate materials in alkaline media. However, in such case, the kinetics of hydrogen oxidation reaction (HOR) in the anode is two orders of magnitude sluggish than that of acidic electrolytes, which is recognized as the grand challenge in this field. Herein, we report the rationally designed Ni nanoparticles encapsulated by N‐doped graphene layers (Ni@NG) using a facile pyrolysis strategy. Based on the density functional theory calculations and electrochemical performance analysis, it is witnessed that the rich Pyridinic‐N within the graphene shell optimizes the binding energy of the intermediates, thus enabling the fundamentally enhanced activity for HOR with robust stability. As a proof of concept, the resultant Ni@NG sample as the anode with a low loading (1.8 mg cm−2) in AEMFCs delivers a high peak power density of 500 mW cm−2, outperforming all of those of NPMC‐based analogs ever reported. [ABSTRACT FROM AUTHOR]

This study explores a symmetric configuration approach in anion exchange membrane (AEM) water electrolysis, focusing on overcoming adaptability challenges in dynamic conditions. Here, a rapid and mild synthesis technique for fabricating fibrous membrane‐type catalyst electrodes is developed. Our method leverages the contrasting oxidation states between the sulfur‐doped NiFe(OH)2 shell and the metallic Ni core, as revealed by electron energy loss spectroscopy. Theoretical evaluations confirm that the S–NiFe(OH)2 active sites optimize free energy for alkaline water electrolysis intermediates. This technique bypasses traditional energy‐intensive processes, achieving superior bifunctional activity beyond current benchmarks. The symmetric AEM water electrolyzer demonstrates a current density of 2 A cm−2 at 1.78 V at 60°C in 1 M KOH electrolyte and also sustains ampere‐scale water electrolysis below 2.0 V for 140 h even in ambient conditions. These results highlight the system's operational flexibility and structural stability, marking a significant advancement in AEM water electrolysis technology. [ABSTRACT FROM AUTHOR]

This article details the development of an electrically-responsive bending actuator from a graphene oxide (GO), nanosized-ZnO, and sulfonated poly(vinyl alcohol) (S-PVA) nanocomposite membrane coated with platinum (Pt). The solution-cast S-PVA/ZnO/GO/Pt membrane exhibits an ion-exchange capacity of 1.68 meq g−1 and favorable electrochemical characteristics. With a 67.28% water uptake after a 4 h immersion at 45 °C, it serves as the foundation for an ionic polymeric-metal composite (IPMC) actuator. Electrolessly plated Pt layers ensure slow water loss (31.6% after 12 min at 6 V), enhancing long-term durability. Electromechanical characterization reveals a 10 mm tip displacement at 3 V, indicating improved investigations. The resulting IPMC nanocomposite with Pt coating demonstrates excellent mechanical, electrical, and electrochemical capabilities for diverse applications. Comprehensive analyses, including SEM, EDX mapping, TGA, and XRD, elucidate the membrane's characteristics. This refined nanocomposite holds promising potential across various applications, offering enhanced invetigations and durability in electrically-driven actuation systems. [ABSTRACT FROM AUTHOR]

This paper presents a detailed techno-economic review and assessment of a hydrogen refueling station (HRS) powered by a grid-connected photovoltaic (PV) system to address the issues of carbon emissions and energy sustainability in transportation. In the study, the HRS system with 1, 3 and 5 MW PV installed capacity for Ankara, the capital city of Türkiye, is considered for different system lifetimes. In the proposed HRS, on-site hydrogen production is achieved through anion exchange membrane water electrolysis (AEMWE) using a grid-connected PV system, and the produced hydrogen is stored in a cascaded storage system and is utilized at the HRS station. In order to evaluate the cost competitiveness and economic viability of the designed HRS system, the levelized cost of hydrogen (LCOH) is determined by considering the initial investment costs, operating expenses and potential revenue streams. The results show that the HRS capacity, PV installed capacity and system lifetime significantly impact the LCOH. The technoeconomic analysis results show that the best system configuration was determined as 8.54 €/kg H 2 in the 20-year long term refueling scenario for a 5 MW installed PV capacity with a daily refueling capacity of 170 kg H 2. This study contributes to the development of sustainable energy infrastructure by providing a comprehensive framework for the design, calculation and economic evaluation of PV-integrated hydrogen refueling stations. The results provide valuable information for policymakers, industry stakeholders, and researchers to help achieve a carbon-neutral transportation sector and promote energy sustainability. • PV integrated onsite hydrogen refueling station is proposed. • Techno-economic evaluation of the HRS was conducted. • The lowest levelized cost of hydrogen (LCOH) was obtained as 8.54 €/kg H 2. • HRS infrastructure required to support hydrogen vehicles through the carbon zero transition. [ABSTRACT FROM AUTHOR]