Theoretical design of two-dimensional visible light-driven photocatalysts for overall water splitting

Hydrogen production from water via photocatalytic water splitting has attracted great interest due to the increasing challenge from energy and environment. The light harvest, electron–hole separation, and catalytic activity are keys to enhance the efficiency of solar energy utilization, which stimulates the development of high-performance photocatalysts. In recent years, two-dimensional (2D) materials have attracted much attention due to their extremely large specific surface area, shortened carrier migration path, and excellent optical properties, but it is still a challenge to realize overall water splitting under visible light with 2D material photocatalysts experimentally. Density functional theory-based first-principles calculations provide a quicker and lower cost approach in material design than experimental exploration. In this review, recent advances in design of 2D material photocatalysts, including metal-containing, metal-free, and heterojunction materials, for photocatalytic water splitting are presented from a theoretical perspective. Future opportunities and challenges in theoretical design of 2D material photocatalysts toward overall water splitting are also included.