Two-dimensional tetragonal GaOI and InOI sheets: In-plane anisotropic optical properties and application to photocatalytic water splitting
Abstract
Layered Bismuth oxyhalides have recently generated considerable interest in various fields, including photocatalysis. However, the properties of previously synthesized layered Group-IIIB oxyhalides (MOX; M = Ga, In, Tl, X = Cl, Br, I) remain unclear.
Here, we systematically investigated the structure, electronic, optical, and photocatalytic properties of two-dimensional MOX nanosheets by density functional theory (DFT) using a hybrid functional. All MOX were predicted to be indirect gap semiconductors with band gaps ranging from 0.88 to 5.16 eV.
Among these semiconductors, InOI and GaOI monolayers have the most favourable band gaps (2.22 and 2.04 eV, respectively) and band edge positions. Therefore, these monolayers are promising photocatalysts for water splitting.
Furthermore, they show anisotropic visible-light absorption and electron-hole effective masses, which can effectively promote the migration and separation of photo-generated electron-hole pairs. Moreover, the band edge positions of InOI and GaOI can be shifted by strain to more suitable regions towards enhancing their photocatalytic activities, and their kinetic and thermal stability has also been confirmed.
In conclusion, this study reports a new type of 2D materials suitable for photocatalytic water splitting.