Modulation of the interfacial charge density on Fe2P–CoP by coupling CeO2 for accelerating alkaline electrocatalytic hydrogen evolution reaction and overall water splitting

Modulating the electronic structure of an electrocatalyst via interface engineering is a promising strategy to accelerate the overall electrocatalytic water splitting. In this work, a novel three-phase heterojunction Fe2P–CoP/CeO2 is constructed via interface engineering combined with a selective phosphorization process. Coupling CeO2 at the interface of Fe2P and CoP effectively promotes the redistribution of electrons at the three-phase interface, which optimizes the Gibbs free energy of H* adsorption energy and significantly reduces the water dissociation energies, thus boosting the electrocatalytic water splitting in alkaline media. As a result, the Fe2P–CoP/CeO2-20 exhibits excellent performances toward HER (η10=45 mV, η50= 100 mV) and OER (η10=248 mV, η50= 278 mV). Moreover, an overall water splitting electrolyzer constructed by Fe2P–CoP/CeO2-20 only requires a cell voltage of 1.52 V to deliver a current density of 10 mA cm−2. Interestingly, the assembled electrolyzer can also be driven by a solar panel for overall water splitting. This work offers a feasible strategy for regulating the electronic structure of three-phase heterojunction interface to promote electrochemical water splitting.