A recent approach for solar‐to‐hydrogen generation has been water electrolysis using efficient, stable, and inexpensive bifunctional electrocatalysts within strong electrolytes. Herein, the direct growth of 1D NiCo2S4 nanowire (NW) arrays on a 3D Ni foam (NF) is described. This NiCo2S4 NW/NF array functions as an efficient bifunctional electrocatalyst for overall water splitting with excellent activity and stability. The 3D‐Ni foam facilitates the directional growth, exposing more active sites of the catalyst for electrochemical reactions at the electrode–electrolyte interface. The binder‐free, self‐made NiCo2S4 NW/NF electrode delivers a hydrogen production current density of 10 mA cm–2 at an overpotential of 260 mV for the oxygen evolution reaction and at 210 mV (versus a reversible hydrogen electrode) for the hydrogen evolution reaction in 1 m KOH. This highly active and stable bifunctional electrocatalyst enables the preparation of an alkaline water electrolyzer that could deliver 10 mA cm–2 under a cell voltage of 1.63 V. Because the nonprecious‐metal NiCo2S4 NW/NF foam‐based electrodes afford the vigorous and continuous evolution of both H2 and O2 at 1.68 V, generated using a solar panel, they appear to be promising water splitting devices for large‐scale solar‐to‐hydrogen generation.

Most reported catalysts for water oxidation undergo in situ electrochemical tuning to form the active species for their oxygen evolution reaction (OER). In general, the in situ electrochemical transformations of non-oxide catalysts are faster than those of the corresponding oxides, and they typically display improved OER activity. Although many approaches for tuning the active surfaces of catalysts as well as investigations into their roles in the mechanism of adsorption of OER intermediates have been reported, we still have a poor understanding of the dominant active sites formed during the OER. This review highlights current progress into the in situ electrochemical tuning with non-oxide catalysts (especially chalcogenides and pnictides) and offers a comprehensive summary of approaches for the enhancement of OER activity. We describe the non-oxide catalysts that have exhibited promising OER performance with strong in situ electrochemical tuning. We also discuss the preoxidation peak positions of the catalysts in alkaline electrolytes. Furthermore, we explore the probability of new active surface formation on non-oxide catalysts with modified OER mechanisms and the collections of available in situ and ex situ methods to identify the active sites in real-time. Finally, we discuss the challenges affecting the future detection of the active sites of the most promising OER catalysts.

Functionalizing nanostructured carbon nanofibers (CNFs) with bimetallic phosphides enables the material to become an active electrode for multifunctional applications. A facile electrospinning technique is utilized for the first time to develop NiCoP nanoparticles encapsulated CNFs that are used as an energy storage system of supercapattery, and as an electrocatalyst for oxygen reduction, oxygen evolution, and hydrogen evolution reaction in KOH electrolyte. Evolving from the inclusion of bimetallic phosphide nanoparticles, the NiCoP/CNF electrode unveils superior‐specific capacitance (333 Fg−1 at 2 Ag−1) and rate capability (87%). The fabricated supercapattery device offers a voltage of 1.6 V that supplies a remarkable energy density (36 Wh kg−1) along with an improved power density (4000 W kg−1) and unwavering cyclic stability (25 000 cycles). Meanwhile, the NiCoP/CNF electrode has simultaneously performed well as a multifunctional electrocatalyst for oxygen reduction reaction at a half‐wave potential of 0.82 V versus reversible hydrogen electrode and can attain a current density of 10 mA cm−2 at a very low overpotential of 268 and 130 mV for the oxygen evolution reaction and hydrogen evolution reaction, respectively. Thus, the NiCoP/CNF with all its inimitable electrode properties has profoundly proved its proficiency at handling multifunctional challenges in terms of both storage and conversion.

The inexpensive fabrication of nano-honeycomb structured nickel iron sulphides on a nickel foam current collector is described and used as both anode and cathode in the alkaline membrane water electrolysis.

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The oxygen electrode plays a vital role in the successful commercialization of renewable energy technologies, such as fuel cells and water electrolyzers. Here, we report the Prussian blue analoguederived nitrogen-doped, nanocarbon layer-trapped, cobalt-rich, core-shell nanostructured This article is protected by copyright. All rights reserved. 2 electrocatalysts (core-shell Co@NC). Our electrode exhibits an improved oxygen evolution activity and stability compared to that of the commercial noble electrodes. The core-shell Co@NC-loaded nickel foam exhibits a lower overpotential of 330 mV than that of IrO 2 on nickel foam at 10 mA cm -2 and had a durability of over 400 h. The commercial Pt/C cathode-assisted, core-shell Co@NC-anode water electrolyzer delivers 10 mA cm -2 at a cell voltage of 1.59 V, which is 70 mV lower than that of the IrO 2 -anode water electrolyzer. Over the long-term chronopotentiometry durability testing, the IrO 2 -anode water electrolyzer shows a cell voltage loss of 230 mV (14%) at 95 h, but the loss of the core-shell Co@NC-anode electrolyzer is only 60 mV (4%) after 350 h of continuous operation, which indicates it is a suitable electrode to replace noble metal oxide anodes for water electrolysis. Our findings indicate that the Prussian blue analogue is a class of inorganic nanoporous materials that can be used to derive metal-rich, core-shell electrocatalysts with enriched active centers.

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High entropy alloys (HEA), the multicomponent (5 or more) alloys with an equiatomic or a near equiatomic composition, provide a unique platform to engineer surface composition and active sites for...