Surface reconstruction induced in situ phosphorus doping in nickel oxides for an enhanced oxygen evolution reaction

Abstract

Surface reconstruction of non-oxide electrocatalysts for the oxygen evolution reaction (OER) to form “true” active species has been reported; however, the mechanism of the in situ surface activation has remained unclear. In this work, nanocrystalline Ni₅P₄ is prepared as a pre-catalyst for the OER to gain insight into the in situ surface activation. We find that NiO nanosheets with abundant crystal defects are formed on the surfaces of Ni₅P₄ particles during the electrochemical process. The effects of the in situ P incorporation in surface reconstruction derived NiO for OER electrocatalysis are discussed. Theoretical calculations reveal that the heteroatom P substitution for O atoms of NiO crystals on the subsurface can weaken the binding strength of the OER intermediates, change the potential-determining step of the OER and achieve a lower theoretical overpotential. The present work provides a novel mechanism of the enhanced electrocatalytic performances of non-oxide materials for OER electrocatalysis by highlighting the effects of surface reconstruction induced in situ heteroatom doping in derived active materials.