Density functional theory calculation on two-dimensional MoS2/BiOX (X = Cl, Br, I) van der Waals heterostructures for photocatalytic action

• DOI: 10.1016/j.apsusc.2019.06.201
• Publication Date: 2019-06-22T10:20:20Z
• Authors: Bin Gao; Jin-Rong Zhang; Lang Chen; Junkang Guo; Sheng Shen; Chak-Tong Au; Shuang-Feng Yin; Meng-Qiu Cai
• Keywords: 01 natural sciences; 7. Clean energy; 0104 chemical sciences

Abstract Bismuth oxyhalide (BiOX)-based heterostructures have attracted much attention due to their promotion effect on photocatalytic performance. Nonetheless, there is a lack of theoretical understanding on the relationship between the BiOX-induced interface and the enhancement of photocatalytic activity. In the present work, density functional theory (DFT) calculations were conducted to investigate the energy band structure, charge transfer and optic properties of layered MoS 2 /BiOX (X = Cl, Br, I) van der Waals (vdW) heterojunctions. All the MoS 2 /BiOX heterojunctions have lower band gaps, smaller effective mass and better light absorption ability than BiOX monolayers. Moreover, electrons transfer from MoS 2 to BiOX, and MoS 2 /BiOX heterojunctions show typical type-II band arrangement. Importantly, MoS 2 /BiOI presents significant performance in the carrier mobility and light absorption ability among the three heterostructures, which can facilitate effective separation of photo-generated electron-hole pairs and enhance photocatalytic activity. It is disclosed that the band edges MoS 2 /BiOX are suitable for the photocatalytic decomposition of water into oxygen. It is especially so for MoS 2 /BiOI which can affect full photocatalytic water splitting. The results clarify why the combination of MoS 2 and BiOX for the generation of MoS 2 /BiOX vdW heterojunctions could result in excellent photocatalytic activity, and disclose why MoS 2 /BiOI is the best among the three for photocatalytic water splitting.