External uniaxial compressive strain induced built-in electric field in bilayer two-dimensional As2S3 for photocatalytic water splitting: A first-principles study

Abstract Water splitting to produce H2 through photocatalysis is an attractive means to deal with the energy crisis, and a built-in electric field is rather crucial for the separation of photogenerated carriers. In this study, by applying uniaxial strain on mono- and bilayer As2S3, the strain-tunable electronic and optical properties feature a strong anisotropy in 2D As2S3. The band edges under all strain conditions are found to meet the potential redox rule of water splitting. The built-in electric field, deduced by the compressive uniaxial strain along a direction in bilayer As2S3, is beneficial to separate the photogenerated carriers and thus improves the photocatalytic efficiency. The optical absorption shows that 2D As2S3 is rather suitable for photocatalytic water splitting in the ultraviolet region. Our findings provide enlightenment to realize the built-in electric field in a bilayer structure, not by substituting atom but by applying strain only.