Electronic states and photocatalytic performances of SnS₂-based binary and ternary vdW heterostructures

Under the framework of the first principles theory, the SnS₂ based binary and ternary heterostructures including h-BN/SnS₂, g-C₃N₄/SnS₂, ZrS₂/SnS₂, h-BN/g-C₃N₄/SnS₂, h-BN/ZrS₂/SnS₂, g-C₃N₄/h-BN/SnS₂, g-C₃N₄/ZrS₂/SnS₂, ZrS₂/h-BN/SnS₂ and ZrS₂/g-C₃N₄/SnS₂ are systematically studied. The absolute values of lattice mismatches (|η|) of binary and ternary heterostructures do not exceed 3.87% and 1.93%, respectively. The negative formation energies also prove the stable states. The band gaps of all the heterostructures are in the range of 1.44 eV–1.91 eV and suitable to water decompostion. The charge transfer in the h-BN/g-C₃N₄/SnS₂, h-BN/ZrS₂/SnS₂, g-C₃N₄/h-BN/SnS₂, g-C₃N₄/ZrS₂/SnS₂, ZrS₂/h-BN/SnS₂ and ZrS₂/g-C₃N₄/SnS₂ heterostructures are 3.66, 1.12, 2.45, 0.57, 5.61 and 5.64 times as large as the charge transfer in the corresponding binary heterostructures. The heterostructures are sorted into Z-scheme, Type-I, Type-II/Z-scheme, Z-scheme/Type-I and Z-scheme/Z-scheme taking into account the synergistic effects of band edges and built-in electric field. Particularly, the Re and Ox centers are located in different layers of the heterostructures which can efficiently separate the photogenerated electron-hole pairs in space, and except ZrS₂/SnS₂, all the other heterostructures can be used to conduct spontaneous full water decomposition. Moreover, the ternary heterostructures have stronger absorption intensities with red shift absorption edges compared with the isolated nanosheets and binary heterostructures, which could be a better choice for enhanced photocatalytic performances under visible light.