Engineering Electronic Structures of Nickel Cobalt Phosphide via Iron Doping for Efficient Overall Water Splitting

Abstract Efficient and low‐cost bifunctional OER/HER electrocatalysts are important for overall water splitting. Herein, three‐dimensional self‐supported Fe‐doped NiCo‐based phosphide nanosheets arrays are in ‐ situ grown on carbon fiber paper. The catalyst shows superior bifunctional activity, with an OER overpotential of 230 mV and an HER overpotential of 95 mV at 10 mA cm −2 in alkaline electrolyte. It is evidenced that the Fe doping facilitates electron transfer from Co/Ni to P, thus optimizing the electronic structures of both Ni and Co active sites, in turn greatly enhancing intrinsic OER and HER activities. The OER and HER turnover frequency are largely improved after Fe doping. When used as both anode and cathode for water splitting, the catalyst enables the electrolyzer to achieve 10 mV cm −2 at a low cell voltage of 1.59 V with a long‐term stability up to 35 h. This work highlights the synergy effect of multi‐metal‐based phosphides for efficient water electrocatalysis.