Strain-induced ultrahigh power conversion efficiency in BP-MoSe2 vdW heterostructure

Abstract

Photocatalytic water splitting is a promising method for hydrogen production, and the search for efficient photocatalysts has received extensive attention. Two-dimensional van der Waals (vdW) heterostructures have recently been considered excellent candidates for photocatalytic water splitting. In this work, a BP-MoSe2 vdW heterostructure composed of a blue phosphorus (BP) and MoSe2 monolayer was studied as a potential photocatalyst for water splitting using first-principles calculations. The results show that the heterostructure has a type-II band structure, and the band edges straddle water redox potentials under biaxial strains from −3% to 2%, satisfying the requirements for photocatalytic water splitting. In addition, the heterostructure has excellent power conversion efficiency (PCE) and strong optical absorption in both visible light and near-ultraviolet region, indicating that it is a very promising candidate for photocatalytic water splitting. Specifically, the PCE was enhanced to ∼20.2% under a tensile strain of 2%. The Gibbs free energy profiles indicate that BP-MoSe2 vdW heterostructure exhibits good catalytic performance in hydrogen and oxygen evolution reactions. In particular, high carrier mobility implies that the transfer of carriers to reactive sites is easy, and the recombination probability of photogenerated electron–hole pairs is reduced.