Strain and Electric Field Engineering of G-ZnO/SnXY (X, Y = S, Se) S-Scheme Heterostructures for Photocatalyst and Electronic Device Applications: A Hybrid DFT Calculation
Yue Tang, YiPeng Wang, Xinlu Cheng, Hong Zhang
Abstract
Using hybrid density functional theory calculations, we systematically study the biaxial strain and electric field modulated electronic properties of g-ZnO/SnS 2, g-ZnO/SnSe 2, and g-ZnO/SnSSe S-scheme van der Waals heterostructures (vdWHs). g-ZnO/SnS 2 and g-ZnO/SnSSe are found to be promising photocatalysts for water splitting with high solar-to-hydrogen efficiencies, even under acidic, alkaline, and high-stress conditions. The strain effect on the bandgaps of g-ZnO/SnXY is explained in detail according to the correlation between geometry structure and orbital hybridization of SnXY, which could help understand the strain-induced band structure evolutions in other SnXY (X, Y = S, Se)-based vdWHs. It is surprising that under an external electric field, g-ZnO/SnS 2, g-ZnO/SnSe 2, and g-ZnO/SnSSe can offer the occupied nearly free-electron (NFE) states. In many materials, NFE states are usually unoccupied and is not conducive to the charge transport. The NFE state in g-ZnO/SnSe 2 is the most sensitive to the electric field and might be promising electron transport channel in nanoelectronic devices. g-ZnO/SnSe 2 might also have application potential in gas sensors and high-temperature superconductors.