Hybrid density functional study on the photocatalytic properties of AlN/MoSe2, AlN/WS2, and AlN/WSe2 heterostructures

Abstract

Hybrid density functional has been adopted to theoretically investigate the structural, electronic, and optical properties of AlN/MoSe2, AlN/WS2, and AlN/WSe2 heterostructures with the consideration of effects of strains and pH so as to explore their potential visible light photocatalytic activities for water splitting. AlN/MoSe2, AlN/WS2, and AlN/WSe2 heterostructures with proper strains are energetically favorable due to the good lattice mismatch and the interface adhesion energies between the constituent monolayers. The charge accumulation/depletion around the interfaces of these heterostructures are beneficial for the generation and separation of photogenerated carriers, which is also favorable for improving the photocatalytic activities. Through adjusting the strains and the pH of the electrolyte, the AlN/MoSe2, AlN/WS2, and AlN/WSe2 heterostructures could own suitable bandgaps for absorbing visible light and appropriate band edge positions with respect to water redox levels for the spontaneous generation of hydrogen and oxygen. The band edge positions of AlN/MoSe2, AlN/WS2, and AlN/WSe2 heterostructures are thermodynamically feasible for over water splitting when the pHs of the electrolyte are respectively around 13, in the range of 4.5–8.1, and greater than 10.7. These findings pave a way to design the efficient AlN-based heterostructures for visible light photocatalytic water splitting.