Electronic structure and optical properties of BiOI {001} monolayer under biaxial strain

The photocatalytic properties of BiOI {001} monolayer are studied through density functional theory computations. The first-principle calculation results indicate that the structural stability of BiOI {001} monolayer under tensile strain is better than that under compressive strain. The band gap is decreasing gradually from compressive strain to tensile strain. Due to its smaller electron effective mass and the larger probability of carriers located in VBM and CBM, the electron transition ability of monolayer is also improved under tensile strain. In addition, the photoabsorption edges will give rise to a redshift for BiOI {001} monolayer under tensile strain, indicating that the utilization of visible-light region is broadened; thus, the photocatalytic performance is improved. So combined with its better structural stability and the better photoelectric properties, we prefer to apply appropriate tensile strain to BiOI {001} monolayer to improve its photocatalytic performance for practical applications.