Two-dimensional MoSeO/BP heterostructure for superior Z-scheme photocatalytic water splitting

The photocatalytic efficiency of traditional photocatalysts is usually frustrated by the easy recombination of photogenerated carriers and the lack of good compatibility between strong redox capacity and light response range. Two-dimensional (2D) Z-scheme heterostructures photocatalysts can solve these problems well. Based on first principles, the photocatalytic properties of 2D MoSeO/Boron phosphide (BP) heterostructures are systematically investigated. The results show that O-Mo-Se/BP heterostructure (with Se atoms close to BP layer) is a traditional type-II heterostructure, which lacks the redox capacity for photocatalytic water decomposition. However, Se-Mo-O/BP heterostructure (with O atoms close to BP layer) is a Z-scheme heterostructure, the builtin electric field can effectively separate the photogenerated carriers with higher redox ability. Meanwhile, the band edge positions with higher redox capacity straddle the water redox potentials for water splitting. Optical absorption shows that the heterostructure has a good light absorption capacity in UV-visible region. The power conversion efficiency (PCE) for this heterostructure is 15.9 %, which can be further improved to 18.7 % under external electric field. These results indicate that Se-Mo-O/BP heterostructure is a compelling direct Z-scheme candidate for photocatalytic water splitting.