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

Abstract

Heterostructures have attracted extensive attention due to their van der Waals interactions between layers. The photocatalysts of Two-dimensional (2D) heterostructure based on MoS2 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 MoS2/TiO2 heterostructures by using first-principles calculations. The result shows that both MoS2/TiO2(100) and MoS2/TiO2(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 MoS2/TiO2(100) and MoS2/TiO2(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 MoS2/TiO2(001) and 0.52 eV of MoS2/TiO2(100)) cause the entire visible light region can be covered by the light absorption spectrum. The result is that building heterostructures of TiO2 with MoS2 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 MoS2 and deep comprehension of their physical mechanism.