Regulating catalytic kinetics in nanoclimbing-wall-like NiO/NiCoP hybrids for enhanced overall water splitting

Abstract

Developing integrated cost-efficient bifunctional electrocatalysts with unique architecture comparable to noble metal is greatly desirable for efficient electrocatalytic water splitting. Herein, a highly active NiO/NiCoP hybrid catalyst on nickel foam (NiO/NiCoP/NF) with unique nanoclimbing-wall structure is constructed, which is believed to simultaneously improve electron transfer efficiency and catalytic activity. The resultant NiO/NiCoP/NF exhibits outstanding electrocatalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH, featuring low overpotential of 92 and 216 mV at 10 mA cm-2. Two-electrode system based on NiO/NiCoP/NF||NiO/NiCoP/NF requires as low as 1.56 V to deliver the current density of 10 mA cm-2. Theoretical calculations and in-situ Raman characterizations reveal that the positively synergy between NiCoP and NiO endows NiO/NiCoP/NF with accelerated HER and OER kinetics. Moreover, a high solar-to-hydrogen (STH) conversion efficiency is up to 12.40% by using NiO/NiCoP/NF as both cathode and anode in a solar-driven water splitting system. This work provides a promising strategy for the construction of an innovative bifunctional electrocatalyst for efficient overall water splitting and the establishment of a synergistic catalytic mechanism.