Recent progress in Mott-Schottky junction electrocatalysts for the pH-universal hydrogen evolution reaction

The development of efficient electrocatalysts to reduce the overpotential for the pH-universal hydrogen evolution reaction (HER) is necessary for the large-scale industrialization of hydrogen energy. Over the past several decades, a large number of preparation strategies for efficient electrocatalysts have been developed, and various exploration efforts have been made to improve mass transport and expose more active sites. Electrostatic potential energy at the Mott-Schottky heterojunction interface formed by the electron transfer between metals and semiconductors can effectively regulate the electronic structure of the catalyst, provide more new active sites and accelerate charge transfer, in which the built-in electric field promotes local charge polarization at the heterojunction interface and greatly improves the adsorption of critical reaction intermediates, leading to enhanced electrocatalytic activity. This paper reviews the recent research progress of Mott-Schottky heterogeneous electrocatalysts, with a summary of following topics: (a) the formation mechanism of Mott-Schottky heterogeneous catalysts is presented; (b) Mott-Schottky effects on the interfacial charge distribution, d-band center and hydrogen adsorption energy are introduced; (c) the effects of Mott-Schottky heterostructures on the catalytic performance are systematically discussed; and (d) challenges and prospects are given. This review can provide a deep understanding of the microscopic mechanism of Mott-Schottky heterogeneous catalysis and can be extended to design other transition metal-based catalysts. Pathways for the hydrogen evolution reaction under acidic and alkaline (or neutral) conditions.