Computational prediction of two-dimensional o-Al2N2 under applied strain for boosting the photocatalytic hydrogen evolution reaction performance

Abstract

Photocatalytic water splitting for clean hydrogen fuel production provides a promising approach to solve the energy and environmental issues. Recently, two-dimensional (2D) photocatalysts have attracted growing interest owing to their short carrier diffusion path, abundant active sites and large surface area. This study explores the photocatalytic performance of 2D orthorhombic dialuminum dinitride (o-Al2N2) using density functional theory. The computational results show that the o-Al2N2 monolayer has a semiconductor character with indirect and moderate bandgap. Moreover, this system exhibits high light absorption in the visible region, referring to its high capacity for harvesting sunlight. Meanwhile, under neutral pH, the band edge positions are suitable to straddle water redox potentials and the hydrogen evolution reaction is energetically favorable to allow hydrogen production on the surface of 2D o-Al2N2 compound. More importantly, the photocatalytic activity of o-Al2N2 monolayer is significantly improved under slight biaxial compressive strain. Therefore, our findings suggest that the o-Al2N2 nanomaterial is a highly efficient 2D photocatalyst for hydrogen production via water splitting under neutral pH.