Considering the spin–orbit coupling effect on the photocatalytic performance of AlN/MX2 nanocomposites

Abstract

The enhanced photocatalytic mechanisms for the hybrid AlN/MX₂ (MX₂ = MoSe₂, WS₂, and WSe₂) nanocomposites are systematically investigated by density-functional-theory calculations. Our theoretical calculations study the photocatalytic performance of AlN/MX₂ nanocomposites with the inclusion of the spin–orbit coupling (SOC) effect. The results demonstrate that the band gaps of the AlN/MX₂ bilayers vary from 1.72 to 1.93 eV, covering the main region of the visible light. All of the AlN–MX₂ bilayers exhibit prominent visible and UV light response compared to their individual constituents, implying their potential applications as excellent light-absorbers. The AlN–MX₂ heterobilayers are excellent photocatalysts for splitting water into hydrogen due to the perfect fit of band edge positions with respect to water reduction and oxidation potentials. Particularly, AlN–WS₂ has type-II band alignment. Besides, the applied small biaxial tensile strain can not only effectively tune the band edge positions, but can also trigger an indirect–direct band gap transition in AlN–MX₂ bilayers maintaining the excellent optical properties. Therefore, the strained AlN–MX₂ bilayers are expected to be more promising candidates for photocatalysis. Overall, our theoretical predictions point toward the prospective future of novel AlN–MX₂ heterostructures for photocatalysis.