Zinc and fluorine ions dual-modulated NiCoP nanoprism array electrocatalysts for efficient water splitting.

Designing efficient, stable, and low-cost bifunctional catalysts for overall water splitting is significant but challenging. In this work, Zn and F ions co-doped NiCoP nanoprism arrays grown directly on nickel foam (Zn/F-NiCoP/NF) was synthesized via hydrothermal method followed by phosphorization treatment. The resultant Zn/F-NiCoP/NF exhibits high electrocatalytic activity towards hydrogen evolution reaction (HER, η10 = 59 mV) and oxygen evolution reaction (OER, η50 = 285 mV). An alkaline electrolyzer using Zn/F-NiCoP/NF as both cathode and anode requires a low cell voltage of 1.568 V at a current density of 10 mA cm-2 with a high long-term stability of up to 40 h, which outperforms many reported Ni,Co-based catalysts. Density functional theory (DFT) calculations proof that simultaneous doping of NiCoP with Zn and F ions provides flexibility to regulate the electronic configuration and downshifts the transition metal d-band center, thereby optimizing adsorption energy between reactants and intermediates, which enhances the HER and OER catalytic activities. This work highlights that cation-anion co-doping strategy is an effective way to develop highly active transition metal phosphides electrocatalyst for water splitting.