Improving built-in electric fields for effective photocatalytic activity in the rationally designed electron transfer pathway of TiO 2 @MoS 2 /Bi 2 S 3

The efficiency of photocatalytic activity relies on rationally controlling the rapid charge transfer channel and the interfacial electric field. In this article, a ternary TiO 2 @MoS 2 /Bi 2 S 3 is proposed, in which TiO 2 hierarchical microspheres are assembled with MoS 2 nanosheets and Bi 2 S 3 NPs. This assembly generates a substantial surface electrostatic potential difference at the interface, thereby strengthening the built-in electric field. The interfacial potential difference intensity of TiO 2 @MoS 2 /Bi 2 S 3 is 5.6 and 1.8 times greater than that detected in TiO 2 and TiO 2 @MoS 2 , respectively. This considerable increase in the internal electric field significantly speeds up the migration of out-of-plane electrons at the TiO 2 /MoS 2 and MoS 2 /Bi 2 S 3 interfaces. Driven by this enhanced field, TiO 2 @MoS 2 /Bi 2 S 3 exhibits dramatically improved photocatalytic activity under visible light irradiation that is 8.3 times and 2.7 times higher than that of pristine TiO 2 and TiO 2 @MoS 2 on the degradation rate of tetrachlorophenol (4-CP), respectively, along with 6% of incident photon-to-electron conversion efficiency (IPCE). In addition, a mechanism investigation demonstrated that the Schottky barrier is established due to the Fermi level equilibrium and the bending of the energy band, effectively inhibiting the electron backflow. Furthermore, DFT calculations and mechanism investigation revealed that the photo-induced electron transfer route in the direction of MoS 2 efficiently suppressed the electron–hole recombination process, ultimately facilitating the generation of reactive oxygen species (ROS). This work provides a comprehensive understanding of the mechanism for enhancing the built-in electric field via the formation of a dual heterostructure, constituting a promising strategy to design photocatalysts for realizing high-efficiency photocatalytic activity.