Effective orientation control of photogenerated carrier separation via rational design of a Ti3C2(TiO2)@CdS/MoS2 photocatalytic system

摘要

Spontaneous photocatalytic H-2 evolution from solar-driven water splitting is highly attractive for converting abundant solar energy to valuable fuel. Regulation of the direction of photocarriers separation and transport is an important factor influencing solar energy conversion efficiency. Here, structural design and energy band engineering are employed to design and construct a novel Ti3C2(TiO2)@CdS/MoS2 composite photocatalyst. The transfer direction of photogenerated electrons and holes is achieved via rational conjunction of Ti3C2 and MoS2. This well designed photocatalytic system possesses remarkable H2 evolution rate (8.47 mmol h(-1) g(-1)) and excellent photocatalytic stability. Furthermore, a high H-2 yield rate of 344.74 pmol h(-1) g(-1) can be reached in pure water without any electron sacrificial agents. Through combination with the scope of a type II junction between CdS and MoS2, the new Z-scheme between CdS and TiO2 transformed from Ti3C2 sets up a multi-step separation of electron-hole pairs. This process prolongs the lifetime of photogenerated electrons and makes them reach the active sites to initiate an efficient photocatalytic redox reaction. This work demonstrates that the design philosophy of selectively controlling the transfer direction of electrons and holes has promising applications in solar energyutilisation.