2D Triphosphides: SbP3 and GaP3 monolayer as promising photocatalysts for water splitting

Abstract

Two-dimensional (2D) triphosphides, as an important family of 2D materials, have attracted more attention. Here, by using density functional theory (DFT) computations, we explored the remaining XP3 monolayers (X = the metal of group IIIA-VA), and then proposed two novel 2D triphosphides, antimony triphosphide (SbP3) and gallium triphosphide (GaP3) monolayer. SbP3 and GaP3 monolayer are structurally stable semiconductors with indirect bandgaps of 2.36 eV and 1.45 eV, respectively. They not only show strong light absorption coefficients (up to 105 cm−1) in the visible and ultraviolet regions, but also their band edge positions straddle the redox potentials of water, making them promising catalysts for water splitting. Under strain, SbP3 monolayer can effectively reduce the bandgap and GaP3 monolayer can achieve the transition from indirect to direct bandgap, which can improve the photocatalytic efficiency accordingly. Our work would stimulate the fabrication of SbP3 and GaP3 monolayer and explore their potential applications in electronic and optoelectronic devices.