A first-principles research of two-dimensional AlN/C2N van der Waals heterostructure as photocatalyst

Abstract Van der Waals (vdW) heterostructures are ordinarily employed to furnish more possibilities for two-dimensional (2D) semiconductor materials. In this work, we explore thoroughly the electronic and optical properties of AlN/C2N heterostructure based on first-principles. The results reveal that the heterostructure with an indirect bandgap is a semiconductor material that is stable in energy and made by vdW interaction. The AlN/C2N heterostructure has type-II band alignment that can availably facilitate the segregation of photogenerated carriers and prolong the longevity of the carriers, and the built-in electric field (Eint) formed inside the heterostructure can further encourage them. The band edge position crossing the water-splitting redox potential states that the heterostructure can serve to water-splitting catalytic process, while water oxidation and reduction reactions befell in the AlN layer and the C2N layer, respectively. Moreover, the heterostructure has higher carrier mobility and stronger light absorption capacity in the near-ultraviolet and visible light regions compared to two monolayers. It is worth noting that the light absorption of the heterostructure has redshift under compressive biaxial strain. The work demonstrates that the 2D AlN/C2N heterostructure has the compelling potential to be used as an efficient water-splitting photocatalyst and used for other optical devices.