Phosphorus doping to promote the reconstruction of NiS nanorods for efficient electrocatalytic water oxidation

Abstract

Transition metal sulfides have been verified as effective precatalysts for OER in alkaline conditions, and the in-situ reconstructed metal (oxy)hydroxides on their surface were the real active sites. The rational reconstruction can regulate the amount and chemical state of the metal (oxy)hydroxides and thus promote the OER performance efficiently, but also remains a challenge. Herein, we report a unique rationally controllable in-situ anodic electrochemical activation (AEA) strategy to promote the surface reconstruction for the formation of amorphous NiOOH layer onto the P-doped NiS nanorod arrays on nickel foam (P-NiS@NiOOH-aea/NF). The doping of P atom promotes the dissolution of S and accelerates the reconstitution of NiOOH on its surface. The optimized P-NiS@NiOOH-aea/NF through the unique AEA strategy exhibits outstanding OER activity requiring ultra-low overpotentials of 203 and 349 mV to reach 10 and 1000 mA cm−2, respectively, together with robust electrocatalytic stability and satisfactory selectivity (nearly 100% Faraday efficiency) in 1.0 M KOH solution. The density functional theory (DFT) calculations further demonstrate that heteroatomic P-doping reduces the adsorption free energy of intermediate species and enhances the OER intrinsic activity of adjacent nickel active site. This work has a guiding significance for the rational design of introducing anions in the in-situ reconstruction process.