Construction of group III nitride van der Waals heterostructures for highly efficient photocatalyst

Abstract

Photocatalytic water splitting is an effective way to solve the energy crisis and environmental problems. Here, we propose a series of heterostructures constructed by two-dimensional (2D) group III nitrides (AlN, GaN, InN) to filter out high-performance and environment-friendly materials that can work as promising photocatalysts. Using first-principles calculations, we mainly focus on the type-II van der Waals (vdW) heterostructures with high charge transfer and optical absorption properties. Through step-by-step screening, the stacking-V GaN/InN with a direct type-II band gap is found to be the best candidate. The overall water splitting reaction is then investigated for this selected heterostructure. The Gibbs free energy for the hydrogen evolution reaction process is found to be as low as −0.355 eV, which can be further optimized to −0.163 eV under a −2 % compressive strain. Besides, the overpotential for the oxygen evolution reaction process is as low as 0.853 V. All these properties confirm the stacking-V GaN/InN to be a highly efficient visible-light photocatalyst for the water-splitting reaction. This work could provide guidelines on solar energy applications of the group III nitrides heterostructures and contribute to developing the relevant photocatalysis systems.