Prediction of novel penta-Si₃P₂X (X = S, Se) monolayers as photocatalytic materials for water splitting by first principles calculations

In this paper, two-dimensional (2D) semiconductor Si₃P₂X (X = S, Se) monolayers with pentagonal crystal structures called Penta-Si₃P₂X are systematically predicated. According to our computations, the designed 2D monolayers indicated appropriate structural, thermodynamic and dynamic stabilities. The electronic and optical properties of the presented monolayers investigate by performing first-principles calculations according to density functional theory. The obtained results determined Penta-Si₃P₂S and Si₃P₂Se monolayers are indirect semiconductors with band gaps of about 2.28 eV and 2.10 eV obtained by using Heyd–Scuseria–Ernzerhof level of theory. Furthermore, our investigations on the optical properties of these two monolayer materials present acceptable absorption properties in visible region of light. By comparing the absolute positions of proposed monolayers band edges with the redox potentials of water, the predicted 2D Penta-Si₃P₂S and Si₃P₂Se monolayers are qualified materials as photocatalyst in hydrogen generation by water splitting method. (author)