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Co phosphides, although highly active for the hydrogen evolution electrocatalysis in acids, still deliver inferior performance in alkalis, limiting their application in alkaline water electrolysis. Building an effective Co phosphide/(hydroxide)oxide interface could be a viable way to improve the hydrogen evolution activity of Co phosphide catalysts under alkaline conditions, which however remains unexplored and challenging. In this communication, we report the facile development of a CoP–CeO2 hybrid nanosheet film on Ti mesh (CoP–CeO2/Ti) from easily made Co3O4–CeO2via a selective phosphidation strategy. In 1.0 M KOH, such CoP–CeO2/Ti achieves a geometrical catalytic current density of 10 mA cm−2 at a pretty low overpotential of 43 mV, 27 mV less than that for CoP/Ti. Remarkably, our CoP–CeO2/Ti also shows superior durability over CoP/Ti, suggesting that CeO2 greatly stabilizes the CoP catalyst. Density functional theory calculations demonstrate that CoP–CeO2 possesses a lower water dissociation free energy and a more optimal hydrogen adsorption free energy than CoP. This selective phosphidation strategy is universal in engineering the transition metal phosphide/oxide interface for applications. [ABSTRACT FROM AUTHOR]

It is of great importance but still remains a key challenge to develop non-noble-metal bifunctional catalysts for efficient full water splitting under mild pH conditions. In this communication, we report the in situ electrochemical development of an ultrathin Ni–Bi layer on a metallic Ni3N nanosheet array supported on a Ti mesh (Ni3N@Ni–Bi NS/Ti) as a durable 3D core/shell structured nanoarray electrocatalyst for water oxidation at near-neutral pH. The Ni3N@Ni–Bi NS/Ti demands overpotentials of 405 and 382 mV to deliver a geometrical catalytic current density of 10 mA cm−2 in 0.1 and 0.5 M K–Bi (pH: 9.2), respectively, superior in activity to Ni3N NS/Ti and most reported non-precious metal catalysts under benign conditions. It also performs efficiently for the hydrogen evolution reaction requiring an overpotential of 265 mV for 10 mA cm−2 and its two-electrode electrolyser affords 10 mA cm−2 at a cell voltage of 1.95 V in 0.5 M K–Bi at 25 °C. [ABSTRACT FROM AUTHOR]