MoS₂/TiO₂ van der Waals heterostructures for promising photocatalytic performance: a first-principles study

Abstract

Abstract Heterostructures have attracted extensive attention due to their van der Waals interactions between layers. The photocatalysts of Two-dimensional (2D) heterostructure based on MoS 2 have tempted more and more attention because of their eminent photocatalytic performance, but they are still limited by the weak absorption of visible light and lesser conversion efficiency of solar-to-hydrogen. In this work, we exhaustively investigate the electronic, optical and the structural properties of 2D MoS 2 /TiO 2 heterostructures by using first-principles calculations. The result shows that both MoS 2 /TiO 2 (100) and MoS 2 /TiO 2 (001) heterostructures are stable interfaces and direct Z-scheme photocatalysts, which is favourable for the separation and migration of electron and hole pairs under the excitation of light. And what’s more, both the MoS 2 /TiO 2 (100) and MoS 2 /TiO 2 (001) heterostructures exhibit direct band gap at the Γ point, this is conductive to better electronic transition and absorption of light because of lower energy depletion than indirect band gap semiconductors. The relatively small band gap (1.08 eV of MoS 2 /TiO 2 (001) and 0.52 eV of MoS 2 /TiO 2 (100)) cause the entire visible light region can be covered by the light absorption spectrum. The result is that building heterostructures of TiO 2 with MoS 2 advances the absorption of light and hastens the separation and migration of electron and hole pairs, the activity of photocatalysis could be advanced by all of these. The results provide a basis of heterostructure photocatalysts based on monolayer MoS 2 and deep comprehension of their physical mechanism.