Theoretical Advances in Understanding and Designing the Active Sites for Hydrogen Evolution Reaction

As a fundamental step of water splitting and a stepping stone toward exploring other multielectron transfer processes, the electrocatalytic hydrogen evolution reaction (HER) is an ideal model for both fundamental understanding and electrocatalyst design. Here, we review the fundamentals and recent developments of theoretical insights into HER, covering the mechanistic aspects, key activity descriptors, local environment considerations, and advances beyond the computational hydrogen electrode. Although it is experimentally challenging to explore the active sites and mechanisms in the electrocatalytic process, computational and theoretical advances show great potential in identifying active sites and reaction mechanisms. In this Review, we especially focus in depth on theoretical insights in revealing and designing the active sites for HER. Major challenges ahead will also be discussed at the end of the Review.