The high-speed channel made of metal for interfacial charge transfer in Z-scheme g–C₃N₄/MoS₂ water-splitting photocatalyst

Abstract

Abstract Z-scheme heterostructures have attracted much attention for their prominent photocatalytic performance. However, the charge transfer mechanism is still ambiguous, and how to design the high-speed channel for interfacial charge transfer is still a big challenge. In the present work, the energy band structure and charge transfer of the MoS 2 /g–C 3 N 4 heterojunction are studied systematically. MoS 2 /g–C 3 N 4 heterojunction could be demonstrated to form a direct Z-scheme system via the analysis of the interfacial band bending. Regrettably, this heterojunction has a low tunneling possibility at the surface, seriously limiting the photocatalytic efficiency. To solve this problem, we try to build high-speed channel between the layers with suitable metal. We make a thorough inquiry of the interface of M–C 3 N 4 and M–MoS 2 heterojunctions (M = Ag, Al, Au, and Pt). Our results reveals that Ag could improve the recombination efficiency of the majority carriers at the interface, which could pretty explain the enhanced photoactivity for g–C 3 N 4/ Ag/MoS 2 system found in experiments. More notably, both Schottky and tunneling barriers vanish at the Al–C 3 N 4 interface, forming an ohmic contact, which predicts a higher performance for electron transport. So that aluminum with the more excellent performance and higher abundance is a promising candidate for sliver in the Z-scheme system.