Construction of a reversible-cycling bifunctional electrocatalyst CoP2@Co(CO3)0.5OH/Cu/NF with Mott–Schottky structure for overall water splitting

Abstract

In recent years, interchangeable catalysts with combined functions of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have emerged as a focal point in water electrolysis. However, the irreversible decline in catalytic activity has posed a significant challenge for these catalysts. Here, we introduce a recyclable bifunctional electrocatalyst, CoP₂@Co(CO₃)_0.5OH/Cu/NF, for overall water splitting, which can be easily regenerated by simply exchanging the anode and cathode. The samples are prepared by anchoring CoP₂ nanoparticles on the surface of a Co(CO₃)_0.5OH/Cu heterojunction through an in situ generation process. Due to the internal electric field formed by the Mott–Schottky substrate composed of Co(CO₃)_0.5OH/Cu and the sensitization of CoP₂ nanoparticles, the resulting samples exhibit low overpotentials and rapid reaction kinetics for HER and OER catalytic activities. The integrated water decomposition electrolyzer operates efficiently at a decomposition voltage of only 1.56 V to achieve a current density of 20 mA cm⁻². Remarkably, after one stable cycling operation, the sample can regain 100% electrocatalytic efficiency by exchanging the cathode/anode. This pioneering work presents a novel approach to designing high-performance, long-lasting, and bifunctional electrocatalysts suitable for industrial application.