Electrolysis Applications Research Articles

Intercalation of g-C3N4/Ag2S heterostructure on boronized Ni-MOF for enhanced water splitting and energy storage applications

The increasing global demand for energy conversion and storage technologies including water electrolysis, fuel cells, batteries & supercapacitors depend critically on the performance of their electrode components. Metal Organic Frameworks (MOFs), particularly Nickel Zeolite Imidazole Frameworks (Ni-ZIF) have drawn significant attention due to their greater electrocatalytic performance. Still, their restricted active sites & stability hinder their broader implementation in alkaline/saline water electrolysis & supercapacitor applications. Here, we are reporting the intercalation of heterostructure consisting of silver sulfide (Ag2S)/graphitic carbon nitride (g-C3N4) on Boronized Ni-ZIF (B:NZ) for empowered alkaline/saline water splitting and supercapacitor applications. These heterostructure addition over Boronized Ni-ZIF demonstrated minimal overpotentials for the oxygen evolution reaction (OER) (324 mV at 10.0 mA cm-2) and the hydrogen evolution reaction (HER) (78 mV at 10.0 mA cm-2) in alkaline medium (1 M KOH). The observed improvement in activity is ascribed to the decreased charge transfer resistance (Rct) & the augmented electrochemical active surface area (ECSA). Furthermore, Ag2S/g-C3N4/Boronized Ni-ZIF exhibited high specific capacitances of 1076.6 F/g and areal capacitance of 2584 F/cm2 at 0.50 A g-1 in supercapacitor applications. The incorporation of the g-C3N4 layer has enhanced the surface area and roughness facilitating stronger adhesion between hybrid layers which in turn resulted in prolonged stability exceeding 20 h in water splitting and 86 % retention in supercapacitor application.

Research progress of high-entropy oxides for electrocatalytic oxygen evolution reaction.

High-entropy oxides (HEOs), similar to high-entropy materials (HEMs), have "four-core effects", i.e., high-entropy effect, delayed diffusion effect, lattice distortion effect and cocktail effect, which have attracted more and more attention in the scientific field of renewable energy technology due to their unique structural characteristics, variable chemical composition and corresponding functional properties. HEOs have become potential candidates for electrocatalytic oxygen evolution reaction (OER), which is a key half reaction for electrolytic CO2, nitrogen reduction, and water electrolysis. However, the precise synthesis of HEOs with a wide range of components and structures is challenging, not to mention their active and stable operation for OER. In this paper, we review the recent advancements in the electrocatalytic oxygen evolution facilitated by HEOs in water electrolysis. We analyze these developments from the perspectives of activity and stability in acid and alkaline conditions, respectively. Furthermore, we summarize the design from the aspect of element composition, structure, morphology, and catalyst-support interactions, along with related reaction mechanism of HEOs. Additionally, we discuss the current challenges faced by HEOs in the field of OER and suggest potential directions for the future development of HEOs beyond water electrolysis application.

Amorphous/crystalline Ni-Fe based electrodes with rich oxygen vacancies enable highly active oxygen evolution in seawater electrolysis

To realize large-scale production of hydrogen through seawater electrolysis, it is highly crucial to engineer high-activity and robustly stable catalytic materials for oxygen evolution reaction (OER). Here, a facile etching growth strategy based on Ni foam (NF) is employed to fabricate an amorphous/crystalline Ni-Fe based electrode with rich oxygen vacancies as a promising OER electrocatalyst (a/c-NiFeOxHy@NF). Of note, the introduction of Fe induces the generation of plentiful Ni(Fe)OOH species, which can contribute to the remarkable OER behavior. Profiting from the favorable geometric microstructure of ultrathin nanosheets coupled with 3D open-pore architecture and regulated electronic state by increased oxygen vacancies and abundant crystalline-amorphous boundaries, the resulting a/c-NiFeOxHy@NF displays prominent electrocatalytic OER activity in pure alkaline solution and seawater, achieving impressive overpotentials of only 219 and 233 mV to reach 100 mA cm−2, respectively. More significantly, the electrode can keep stable operation without obvious attenuation for over 1200 h at 100 mA cm−2, demonstrating its exceptional corrosion resistance. Such robustness of this electrode surpasses those of almost all reported OER electrocatalysts. Furthermore, in a self-assembled seawater electrolyzer with a/c-NiFeOxHy@NF as the anode and l-RuP@NF as the cathode, a large current density of 500 mA cm−2 is easily achieved at the voltage of 1.795 V at 65 °C. The work offers a novel paradigm for constructing low-cost, high-efficiency, and ultra-stable OER catalysts, which shows huge promise for industrial seawater electrolysis applications.

Boosting the electrocatalytic performance of CuCo2S4 via surface-state engineering for ampere current water electrolysis applications

For the efficient production of green H2 on an industrial scale, developing durable, cost-effective electrocatalysts using earth-abundant transition-metals is crucial. Herein, we report a robust, bifunctional sulfurized CuCo2O4 (CCS/Ov) catalyst with engineered oxygen-vacancies, in which the metal catalyst is tunes to high valence state, significantly altering the intrinsic reaction kinetics and generating better catalytic activity for efficient ion transport in various electrolytes (neutral, seawater, alkaline simulated-seawater (ASW), and KOH). The optimized dual-strategy synthesized CCS/Ov catalysts with hierarchical morphology exhibits modest overpotential of 383 and 355 mV at 1000 mA cm−2 for OER and HER, respectively, in 1 M KOH. Impressively, an electrolyzer cell (CCS/Ov||CCS/Ov) demonstrates low cell-voltage of 1.487 V (6 M KOH), with excellent robustness in an ASW (1 and 2 M) environment against corrosive chlorine. The bifunctional CCS/Ov||CCS/Ov catalyst outperforms a state-of-the-art paired Pt/C||RuO2 catalyst and maintains the lowest potential response at up to 2000 mA cm−2, while demonstrating remarkably stable simultaneous O2 and H2 generation over 10 days at various current rates. Additionally, DFT calculations confirmed that CCS/Ov catalysts demonstrate significantly enhanced HER and OER activities due to reduced H2O dissociation energy and strong intermediate binding energy, which is attributed to the anionic vacancy near Co3+. The excellent bifunctional performance of the hierarchical CCS/Ov highlights its potential as non-precious catalyst with facile fabrication approach.

Room-temperature rapid oxygen monitoring system in high humidity hydrogen gas environment towards water electrolysis application

Water electrolysis is one of the key processes for carbon-free hydrogen (H2) generation, yet it inherently presents the risk of oxygen (O2) permeation, a significant concern that must be addressed. Contrary to external atmospheric conditions, the environment within a water electrolysis system is characterized exclusively by high-purity H2, little O2, and moisture (H2O). However, there has been limited research on sensors capable of detecting O2 crossover in such a pure H2 atmosphere under high humidity conditions. In this study, we developed an electrolysis O2 monitoring (E-OM) sensor based on a semiconducting metal oxide (SMO) that can operate at a room-temperature with such high humidity through photoactivation with 365 nm LED light. A porous In2O3 nanofilm, prepared by glancing angle deposition (GLAD), was used as the gas sensing material, and copper nanoparticles (Cu NPs) were decorated on the In2O3 surface through electron beam evaporation to accelerate the O2 adsorption. Remarkably, the E-OM sensor showed a humidity-independent response to O2 gas in the H2 atmosphere. Meanwhile, since the response of the E-OM sensor itself was not fast enough for water electrolysis system application, convolutional neural network (CNN)-based signal processing in the time domain was applied. As a result, our E-OM sensor system could predict O2 concentrations from 0 to 2 vol% in an H2 environment with a relative humidity (RH) of 30–90 %, and the detection time was under 5 s. This development could enable safe, rapid, and cost-effective monitoring of O2 crossover in H2 production infrastructure.

Multiphase lattice engineering of bimetallic phosphide-embedded tungsten-based phosphide/oxide nanorods on carbon cloth: A synergistic and stable electrocatalyst for overall water splitting

The hierarchical design of the three-dimensional (3D) nanoarchitecture, comprising multiple phases within an interconnected network on a conductive substrate, offers a high specific surface area, abundant exposed active sites, and rapid electron transport. In our study, we synthesized a hybrid catalyst by integrating (Fe,CO)-P nanoparticles into uniformly grown W-(O,P) nanorods on carbon cloth (CC) using a straightforward method, demonstrating notable electrocatalytic performance. The as-synthesized (Fe,CO)-P/W-(O,P)@CC exhibited remarkable performance in both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) for overall water splitting. It achieves overpotentials of 210 and 61.3 mV for the OER and HER, respectively, at a current density of 10 mA cm−2 in a 1 M KOH solution. As a bifunctional electrocatalyst in overall water splitting, (Fe,CO)-P/W-(O,P)@CC needs only 1.50 V to attain a current density of 10 mA cm−2, surpassing traditional Pt/C@CC and IrO2@CC counterparts (1.53 V @ 10 mA cm−2). The synergistic effects between (Fe,Co)-P and the W-(O,P)@CC nanohybrid heterostructure enhance the charge transfer, further promoting the activity of this hybrid electrocatalyst. This study reveals a promising avenue for advanced water electrolysis applications.

In situ hydrothermal growth of Ni-based hydrogen phosphate polyhedrons on Ni foam for efficient hydrogen evolution reaction

Developing a cost-effective and stable electrocatalyst is the key to achieve the large-scale applications of water electrolysis to produce green hydrogen. Herein, an in situ hydrothermal growth strategy was put forward to prepare a novel self-supporting electrode, that is, Ni-based hydrogen phosphate polyhedrons supported on 3D Ni foam. This electrode was composed of crystalline (Ni(H2PO4)2·2H2O, Ni(H3P2O7)2·2H2O), and amorphous phase in which NiO nanoparticles formed. The amorphous phase connected polyhedrons to the Ni foam substrate, forming multifarious heterogeneous interfaces. Such a structure possessed large number of active sites, favored the fast reaction kinetics and electron transport rate, synergistically resulting in a superior alkaline HER performance. In alkaline electrolyte, the electrode only needed a small overpotential of 69 mV to reach the current density of 10 mA cm−2 with a small Tafel slope of 56 mV dec−1, and exhibited a good stability at the current density of 100 mA cm−2 for 50 h. This in situ hydrothermal growth strategy opened up a new route to green synthesis of cost-effective and stable 3D heterostructured self-supporting electrode for water-splitting.

Arrayed metal phosphide heterostructure by Fe doping for robust overall water splitting

Transition metal phosphides (TMPs) show promise in water electrolysis due to their electronic structures, which activate hydrogen/oxygen reaction intermediates. However, TMPs face limitations in catalytic efficiency due to insufficient active sites, poor conductivity, and multiple intermediate steps in water electrolysis. Here, we synthesize a highly efficient bifunctional self-supported electrocatalyst, which consists of an N-doped carbon shell anchored on Fe-doped CoP/Co2P arrays on nickel foam (NC@Fe-CoxP/NF) using hydrothermal and phosphorization techniques. Experimental and theoretical results indicate that the modified morphology, with increased active site density and a tunable electronic structure induced by Fe doping in the CoP/Co2P heterostructure, leads to superior water electrolysis performance. The resulting NC@Fe0.1-CoP/Co2P/NF catalyst exhibits overpotentials of 122 mV for the hydrogen evolution reaction (HER) and 270 mV for the oxygen evolution reaction (OER) at 100 mA cm−2. Furthermore, using NC@Fe0.1-CoP/Co2P/NF as both the cathode and anode in an alkaline electrolyzer enables the cell system to achieve 100 mA cm−2 at a voltage of 1.70 V, while maintaining long-term catalytic durability. This work may pave the way for designing self-supported, highly efficient electrocatalysts for practical water electrolysis applications.

A facile strategy for synthesis of flower-like FeNiS2 nanocomposite via integration of binary metal-organic framework and metal sulfide for enhanced electrocatalytic oxygen evolution reaction

Researchers are looking into boosted functional materials to address the rising demand for enhanced energy storage and efficient catalysts in producing and storing sustainable energy. Here, we report the development of an integrated binary metallic FeNi metal-organic framework (MOF) through a unique method termed reductive electrosynthesis. This MOF provides customized catalytic sites inside a highly porous material by connecting metal cations via 2-amino terephthalic acid connectors. However, the poor electrical conductivity and stability of pristine MOFs have made their practical implementation difficult. A thin FeNiS2/nickel foam (NF) nanocomposite based on the precursor and self-sacrificed FeNi-MOF template was developed to get beyond these restrictions. In addition to improving electrical conductivity, this unique structure supports FeNi-MOF porous structure. As a result, the outstanding functional electrocatalytic performance of FeNiS2/NF on oxygen evolution reaction in alkaline media was observed at low overpotential of ηj10 = 280 mV and a tafel slope of 35 mV/dec. This study provides a feasible way to produce highly stable and active nonprecious electrocatalysts for commercial water electrolysis applications.

Cover Image

In article number EOM2_EV_EOM212484, Ashishi Gaur and co‐workers report a compressive review on effects of lanthanide doping in electrocatalysts for water splitting. This review covers the mechanistic aspects, followed by recent advancements in lanthanide doping and heterostructure formation for water electrolysis applications image

Lanthanides in the water electrolysis

AbstractThe most feasible technique for producing green hydrogen is water electrolysis. In recent years, there has been significant study conducted on the use of transition metal compounds as electrocatalysts for both anodes and cathodes. Peoples have attempted several strategies to improve the electrocatalytic activity of their original structure. One such technique involves introducing rare earth metals or creating heterostructures with compounds based on rare earth metals. The incorporation of rare earth metals significantly enhances the activity by many folds, while their compounds offer structural stability and the ability to manipulate the electronic properties of the original system. These factors have led to a recent boom in investigations on rare earth metal‐based electrocatalysts. There is currently a pressing demand for a review article that can provide a comprehensive overview of the scientific advancements and elucidate the mechanistic aspects of the impact of lanthanide doping. This review begins by explaining the electronic structure of the lanthanides. We next examine the mechanistic aspects, followed by recent advancements in lanthanide doping and heterostructure formation for water electrolysis applications. It is expected that this particular effort will benefit a broad audience and stimulate more research in this area of interest.image

Scaling Up Stability: Navigating from Lab Insights to Robust Oxygen Evolution Electrocatalysts for Industrial Water Electrolysis

AbstractIn the pursuit of sustainable hydrogen production via water electrolysis, paramount importance of electrocatalyst stability emerges as a defining factor for long‐term industrial viability. A thorough understanding and enhancement of stability not only ensure extended catalyst lifetimes but also pave the way for consistent and efficient hydrogen generation. This review focuses on the pivotal role of stability in determining the practical viability of oxygen evolution electrocatalysts (OECs) for large‐scale applications in water electrolysis for hydrogen production. The paper explores the pivotal role of stability over initial activity, citing examples and hypothetical scenarios. First, figures of merits for stability evaluation of the electrocatalyst are explained along with the available benchmarking protocols for stability evaluation. Further, the text delves into various strategies that can enhance the stability of the electrocatalyst which include self‐healing/regeneration pathway, oxygen evolution reaction (OER) mechanism optimization to achieve highly stable OER and stabilization of active metals atoms within the electrocatalyst to inhibit dissolution as a way forward for industrial application. The interplay of stability, activity, and cost is also explained to suit the industrial application of the electrocatalyst. Lastly, it outlines challenges, prospects, and future directions, presenting a guide for advancing OECs in the hydrogen generation landscape.

Key Strategies for Continuous Seawater Splitting for Hydrogen Production: From Principles and Catalyst Materials to Electrolyzer Engineering

AbstractDue to the high cost of ultra‐pure water supply and the mismatch between water sources and renewable energy distribution, the large‐scale production of green hydrogen through seawater electrolysis has generated significant interest. This presents an attractive potential technology within the framework of carbon‐neutral energy production. However, owing to the complex composition of seawater, particularly the competitive oxidation reactions and corrosion issues involving Cl−, seawater electrolysis has suffered from low selectivity and poor stability in oxygen evolution reaction (OER), which severely impact the efficiency of hydrogen production and hinder the practical applications. To further promote in‐depth research and practical applications of seawater electrolysis, this review introduces the principles, key advantages, and challenges of seawater electrolysis. Specifically, the design strategies are categorized for highly active OER electrocatalysts for seawater electrolysis, including catalyst design, design of chemical reaction systems, and other special process design. To ensure long‐term operational stability of seawater electrolysis, various strategies such as employing self‐supporting materials, surface protection strategies, and electrolyzer design, are discussed. Finally, current challenges and future prospects for the industrialization of seawater electrolysis are proposed and discussed. It is expected that this review provides new insights for large‐scale seawater‐based hydrogen production in the future.

Preparation and electrochemistry study of a new Ti-based PbO2 electrode with Ta-Ti-Sn(Ru)Ox interlayer in Cu electrowinning

Copper (Cu) is a crucial non-ferrous material, and in this research, a new composite layered anode, Ti/Ta-Ti-Sn(Ru)Ox/PbO2, was developed for the hydrometallurgical process. The anode was created using thermal decomposition and subsequent electrodeposition, with Ti serving as the matrix and Ta-Ti-Sn(Ru)Ox as the interlayer. The study identified that the optimal molar ratio of Ta:Ti was 4:1, the ideal number of coating layers was 3, and the preparation temperature was 550 °C. The addition of Sn element improved the bonding force of the coating, preventing it from detaching even if it fails, while the inclusion of Ru enhanced the electrode’s service life. Moreover, the deposited PbO2 layer demonstrated a rich porous structure. In a long-cycle copper electrodeposition application, anodes with optimal preparation parameters showed higher current efficiencies and reduced energy consumptions compared to the Ti/Sn-SbOx/PbO2 baseline electrode, energy consumption reduced by 220.8 kWh per ton of copper product. This research presents a valuable strategy for designing and constructing high-performance electrodes for nonferrous electrolysis and other similar applications.

Simple generic self-assembly fabrication of transition metal borates on polyaminophenylboric acid modified foam nickel for highly-efficient overall water splitting

Water electrocatalysis for hydrogen production as a prospect strategy to store renewable energy and reduce carbon emissions has attracted great attention, and exploring water electrolysis catalysts has become a research hotspot for widespread industrial water electrolysis application. Very recently, transition metal borates have been demonstrated great potential for electrocatalytic hydrogen or oxygen evolution in alkaline media. However, a generic method for fabricating transition metal borates as bifunctional oxygen catalysts are still challenging. Herein, through a two-step process including poly-aminophenylboronic acid electrodeposition and subsequent electrostatic self-assembly of transitional metal ions, for the first time, to our best knowledge, a simple and generic approach to fabricate polyaminophenylborate transition metal salt modified nickel foam electrodes (PAB-M/NF, M represents transition metal element) was developed for highly efficient water splitting. As a proof of concept, the obtained PAB-Ru/NF exhibited remarkable bifunctional HER and OER catalytic activities and stability in alkaline medium. To drive the HER and OER with a current density of 10 mA cm−2 in 1 M KOH electrolyte, PAB-Ru/NF only required an overpotential of 14 mV and 301 mV, respectively. Moreover, even at a great current density of 250 mA cm−2, PAB-Ru/NF can exhibit very favorable long-term stability for over 35 h. When assembled into an electrolyzer with PAB-Ru/NF as both the anode and cathode, a current density of 10 mA cm−2 can be achieved at a very low cell voltage of 1.50 V. In addition, the other PAB-M/NF catalysts (M including but not limited to Fe, Co and Ni) prepared by the same way also show excellent bifunctional HER and OER catalytic activities and durability. This study provides a prospective and economically feasible generic approach for developing practical bifunctional catalysts for industrial water electrolysis.

Water Transport Management in a Bipolar Membrane for CO2 Electrolysis Application

Bipolar membranes (BPMs) offer significant potential for electrochemical technologies, especially in CO2 electrolysis. Their unique ability to create pH gradients provides optimum chemical microenvironments at the cathode and anode for efficient, cheap and sustainable CO2 electrolysis. However, state-of-the-art BPMs are limited in their performance due to phenomena such as membrane degradation and membrane dehydration leading to low ionic conductivity, and hence their complete potential for various electrochemical technologies is yet to be realized. Previous studies have identified water transport as one of the main factors limiting the performance of BPM. A multi-physics model of BPM can serve as a useful tool to gain a comprehensive understanding of different performance limiting factors and thereafter propose solutions to overcome these limitations. The goal of the present study is to provide model based design guidelines for a BPM that facilitates efficient water transport, making it a suitable candidate for integration into a zero-gap CO2 reduction electrolyzer operating at industrial-grade performance levels.We have built a 1-D continuum model of a BPM kept in an aqueous (bi)carbonate electrolyte solution, incorporating physical phenomena such as water-dependent transport of ions and neutral species, field-enhanced homogeneous reactions (water-dissociation and acid-base reactions) along with CO2 phase transfer reaction at the BPM-aqueous electrolyte interfaces. The continuum model employs Poisson-Nernst-Planck equations to resolve local chemical species concentration. The effect of the electric field on the equilibrium dissociation constants of various charge-generating homogenous reactions is incorporated. This becomes important especially at interfaces within the domain where a sharp increase in electric field is observed. Unlike previous modeling studies, we also incorporate mass-conservation equation for water transport to resolve local water concentration inside the BPM. Local water concentration influences the transport of species in the BPM through their water-dependent activity and diffusivity. The electric potential distribution is resolved by incorporating water-dependent local permittivity of the BPM.Our model investigates both the reverse and forward bias operational modes of the BPM. In alignment with the experimental observation, in the reverse bias regime, the model identifies a distinct initial phase where current density is limited, with the majority of the current carried by protons and hydroxide ions at low overpotentials. As the potential increases, there's a rapid increase in current density, indicating a breakdown regime caused by an electric field-enhanced water dissociation reaction at the BPM interface. At even higher potentials, the polarization curve enters a third phase where the current density saturates characterized by water transport limitation. This aspect of the BPM polarization curve is uniquely captured by our model. Conversely, in the forward bias mode, as expected we do not observe any limitations due to mass transport, since water is generated at the bipolar junction. Here, the model forecasts a saturation of CO2 in the electrolyte, leading to gas bubbles forming at the BPM interface. To address the issue of water transport limitation, we conduct various parametric studies focusing on different membrane characteristics, such as individual layer thicknesses and their ion exchange capacities. The outcomes of these analyses provide crucial guidelines for optimizing these parameters and enhancing water management in BPM-based systems.

(Invited) Mechanical Properties of Proton Exchange Membranes for Water Electrolysis Applications

Water electrolysers are critical to the advancement of sustainable hydrogen technologies. A key component of proton-exchange membrane water electrolysers (PEMWE) is the ionomer membrane which transports protons and water from the anode to the cathode and physically separates the H₂ and O₂ reaction products. Importantly, the barrier properties of the membrane must be maintained at high differential pressure over the lifetime of the PEMWE. To help predict the mechanical durability and operational safety of the PEMWE, it is important to understand the mechanical properties of the PEM as a function of temperature, differential pressure, and time.The main component of a typical modern PEM is a perfluorosulfonic acid (PFSA) ionomer. PFSAs have a hydrophobic perfluorinated backbone with pendant perfluorinated side chains terminating in sulfonic acid groups. The general chemical structure of PFSAs is understood to result in phase separation into hydrophilic, sulfonate-rich domains that act as transport pathways and hydrophobic, tetrafluoroethylene-rich domains that impart thermomechanical stability. In PEMWE applications, short-side chain PFSAs are a promising alternative to the benchmark Nafion, a long-side chain PFSA. At a given ion-exchange capacity (IEC), the ratio of perfluorinated backbone to sulfonic acid side chain increases as the side chain length decreases. Thus, short-side chain PFSAs may be more thermomechanically stable while maintaining good proton and water transport necessary for PEMWE efficiency.In this work, the mechanical properties of short-side chain PFSAs are investigated as a function of IEC, temperature, differential pressure, and time. Particular focus is given to compressive mechanical measurements to simulate the conditions experienced by the membrane in PEMWE applications. The findings are expected to help inform the design of next-generation membranes for hydrogen technology applications.

Anchoring magic NiCo2O4/NiO on Ni foam as an effective and binder-free electrocatalyst for boosting hydrogen evolution reaction

Electrocatalysts that can sustain water splitting without corrosion are required for large-scale water electrolysis applications. Thus, designing and constructing stable electrocatalysts is known as a crucial role in hydrogen evolution reactions (HER). Herein, NiCo2O4/NiO nanocubes on Ni foam (NF) as a stable electrocatalyst were fabricated successfully by using a facile hydrothermal method. Field Emission Scanning Electron Microscopy (FESEM) confirms the formation of distinct magic NiCo2O4/NiO/NF nanocubes with a size of 50–150 nm. The electrochemical tests indicated that the NiCo2O4/NiO nanocubes possess long stability of about 140 h and exceptional HER activity with a low overpotential of 38 mV at a current density of 10 mA.cm−2 in a 1 M potassium hydroxide (KOH) and a Tafel slope of only 45 mV.dec−1. The obtained results indicated that this level of HER catalytic performance is assigned to the rough surface and synergistic interactions between Ni and Co atoms in the nanocubes. It was also determined that the existence of NiO interface layer causes robust adhesion between NF and NiCo2O4 nanocubes. In addition, this discovery points to an advantageous future for the configuration and synthesis of highly effective, non-precious metal-based electrocatalysts for large-scale hydrogen production via water-splitting.

Semiconductor Heterostructure (SrFe0.3TiO3-ZnO) Electrolyte with High Proton Conductivity for Low-Temperature Ceramic Electrochemical Cells.

In recent years, ceramic cells based on high proton conductivity have attracted much attention and can be employed for hydrogen production and electricity generation, especially at low temperatures. Nevertheless, attaining a high power output and durability is challenging, especially at low operational temperatures. In this regard, we design semiconductor heterostructure SFT-ZnO (SrFe0.3TiO3-ZnO) materials to function as an electrolyte for fuel cell and electrolysis applications. Using this approach, the functional semiconductor heterostructure can deliver a better power output and high ionic and proton conductivity at low operational temperatures. The prepared cell in fuel cell mode has demonstrated excellent performance of 700 mW cm-2 and proton performance of 540 mW cm-2 at the low temperature of 520 °C, suggesting dominant proton conduction. Further, the prepared cell delivers exceptional current densities of 1.18 and 0.38 A cm-2 (at 1.6 and 1.3 V, respectively) at 520 °C in the electrolysis mode. Our electrochemical cell is stable in fuel and electrolysis mode at a low temperature of 500 °C.

Materials descriptors for advanced water dissociation catalysts in bipolar membranes.

The voltage penalty driving water dissociation (WD) at high current density is a major obstacle in the commercialization of bipolar membrane (BPM) technology for energy devices. Here we show that three materials descriptors, that is, electrical conductivity, microscopic surface area and (nominal) surface-hydroxyl coverage, effectively control the kinetics of WD in BPMs. Using these descriptors and optimizing mass loading, we design new earth-abundant WD catalysts based on nanoparticle SnO2 synthesized at low temperature with high conductivity and hydroxyl coverage. These catalysts exhibit exceptional performance in a BPM electrolyser with low WD overvoltage (ηwd) of 100 ± 20 mV at 1.0 A cm-2. The new catalyst works equivalently well with hydrocarbon proton-exchange layers as it does with fluorocarbon-based Nafion, thus providing pathways to commercializing advanced BPMs for a broad array of electrolysis, fuel-cell and electrodialysis applications.