The Janus GePas monolayer for efficient photocatalytic water splitting

The sun is considered an inexhaustible natural energy resource compared to fos-sil fuels. Regarding the limited amount of fuels such as coal and petroleum and their effect on nature, any application that has the ability to harvest the sun-light and produce energy becomes extremely important. One of the potential mechanisms that can remedy the energy demand in the future is photocatal-ysis, and two-dimensional (2D) materials with suitable electronic and optical properties offer new possibilities for photocatalytic applications. Although vari-ous 2D materials have hitherto been specified as adequate candidates, materials with high photocatalytic efficiency for water splitting are still minimal. In this regard, a novel 2D Janus GePAs monolayer is predicted and its capability for photocatalytic water splitting is examined by performing first-principles density functional theory. The GePAs monolayer is shown to possess robust dynamic and thermal stability. The direct electronic band gap in the visible region and band edge positions of the strain-free and strained monolayers are revealed to be convenient for redox reactions in wide pH ranges. The low recombination proba-bility of charge carriers ensured by high and anisotropic carrier mobility enhances the material’s photocatalytic potential. Optical response calculations, including many-body interactions, exhibit significant optical absorption capacity in the UV–visible range. Furthermore, ultra-low exciton binding energy facilitates dis-sociation into free electrons and holes, promoting photocatalytic reactions. Our study suggests GePAs monolayer is an ideal and remarkably promising material to be utilized in visible-light-driven photocatalytic applications.