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Herein, we have reported an easily synthesized CoS2/Ni3S2/CoNiOx water oxidation catalyst with excellent catalytic activity and superior durability. The as-prepared catalyst required overpotential (η) as low as 256 mV to exhibit a current density of 10 mA cm−2 in 1.0 M KOH. Remarkably, it sustained a current density of 1 A cm−2 for one week in 30% KOH solution with only 25 mV increment of η. Thus, it is a hopeful candidate as a highly-effective water oxidation electrode in practical applications. [ABSTRACT FROM AUTHOR]

Developing low-cost, effective, and durable oxygen-evolution catalysts (OECs) is still a huge challenge owing to the uphill thermodynamic reaction and the involvement of a four-electron and four-proton kinetics process. Herein, a facilely prepared NiCoFe(OH)x/NiOOH/NF electrode affords current densities of 10 and 100 mA cm-2 at overpotentials of 223 and 254 mV, respectively, and a Tafel slope as low as 33.5 mV dec-1in 1 M KOH, which is superior to NiCoFe(OH) x/NF electrodes electrodeposited with a traditional method. This electrode also displays surprisingly high durability at a current density of 50 mA cm-2 for over 50 hours under alkaline conditions. Component analysis and an electrochemical study revealed that the catalytic activity enhancement of this newly prepared electrode is mainly attributed to the formation of the electrically conductive NiOOH interlayer. [ABSTRACT FROM AUTHOR]

Abstract: A simple and low‐cost fabrication method is needed to obtain effective and robust heterogeneous catalysts for the oxygen evolution reaction (OER). In this study, an electrocatalyst FeNiOxHy with a hierarchical structure is synthesized on nickel foam by a simple fabrication method through anion exchange from a metal phosphate to a metal hydroxide. The as‐fabricated FeNiOxHy electrode requires overpotentials of 206 and 234 mV to deliver current densities of 10 and 50 mA cm−2, respectively. The catalytic performance of FeNiOxHy is superior to that of most previously reported FeNi‐based catalysts, including NiFe layered double hydroxide. The catalyst also shows good long‐term durability at a current density of 50 mA cm−2 over 50 h with no activity decay under 1  m KOH. By comparison to the directly electrodeposited FeNi hydroxide in morphology and electrochemical properties, the improved activity of the catalyst could be mainly attributed to an enhancement of its intrinsic activity, which was caused by the anion exchange of phosphate to (oxy)hydroxide. Further studies by cyclic voltammetry indicated a stronger interaction between Ni and Fe from the negative shift of the oxidation peak of Ni2+/Ni3+ in comparison with reported FeNiOxHy, which promoted the generation of active Ni3+ species more easily. This work may provide a new approach to the simple preparation of effective and robust OER catalysts by anion exchange. [ABSTRACT FROM AUTHOR]

Earth‐abundant transition metal oxides are considered one of the most promising oxygen evolution reaction (OER) catalysts. However, their intrinsically low electrical conductivity inhibits the fast kinetics for OER. To overcome this drawback, hollow carbon@NiCo2O4 core–shell microspheres (C@NiCo2O4 HSs) are synthesized with enhanced electrocatalytic activity and stability toward OER. The prepared C@NiCo2O4/Ni foam delivers a current density of 10 mA cm−2 at a small overpotential of 268 mV and exhibits a low Tafel slope of 54 mV dec−1. The enhanced OER performance is attributed to the enlarged specific surface area induced by the combination effect between the 1D nanosheet structure and the 3D hollow microsphere structure, and the improved electrical conductivity is ascribed to the carbon core support. [ABSTRACT FROM AUTHOR]