Interfacial electronic coupling of V-doped Co2P with high-entropy MXene reduces kinetic energy barrier for efficient overall water splitting

Abstract

Developing efficient, low-cost non-noble metal-based bifunctional catalysts to achieve excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics in alkaline media is challenging but very meaningful. However, improving the electronic structure of the catalyst to optimize the adsorption of intermediates and reduce the reaction energy barrier is the key to improve the reaction efficiency. Herein, a V-doped Co2P coupled with high-entropy MXene heterostructure catalyst (V-Co2P@HE) was prepared by a two-step electrodeposition and controlled phosphorization process. The analyses of X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and theoretical calculations jointly show that the introduction of V and the strong electron coupling between the two components optimize the adsorption energy of water molecules and reaction intermediates. Benefiting from the abundant active sites and optimizing intermediate adsorption energy and heterogeneous interface electronic structure, V-Co2P@HE has excellent HER and OER activity and long-term stability under alkaline condition. In particular, when assembled as cathode and anode, the bifunctional V-Co2P@HE catalyst can drive a current density of 10 mA cm−2 with only 1.53 V. This work provides new strategies for the application of high-entropy MXene and the design of novel non-noble metal-based bifunctional electrolytic water catalysts.