The piezoelectric field-induced rearrangement of free carriers unlocks the high redox ability of 1T@2H-MoS2/Bi2S3 piezoelectric catalyst

In recent years, odd-layer 2H-MoS2 nanosheets have proved to be promising piezoelectric catalysts to solve environmental pollution problems. To further improve the 2H-MoS2 piezoelectric performance, 1T@2H-MoS2/Bi2S3 heterostructures were prepared using Bi2WO6 as a precursor. Compared with 1T@2H-MoS2, 1T@2H-MoS2/Bi2S3 piezoelectric degradation of methylene blue is significantly improved under dark and ultrasonic conditions. It is attributed to the free carrier separation being facilitated through the type-II heterojunction, and the electron transport paths are optimized by high conductivity 1T-MoS2. In the radical scavenging experiment and ESR measurement, the hydroxyl radicals produced by 1T@2H-MoS2/Bi2S3 are more than those produced by 1T@2H-MoS2 in the piezoelectric catalysis process. It indicates that the piezoelectric field can realize the free carrier rearrangement by adjusting the band structure. Thus, free carriers in the 1T@2H-MoS2/Bi2S3 heterojunction have the opportunity to shift to the position with high redox potential to unlock the higher redox capability compared with the lower redox potential of the original 1T@2H-MoS2 and Bi2S3. In conclusion, this study shows that the piezoelectric field can regulate the free carrier rearrangement in the type-II heterojunction, allowing the type-II heterojunction can not only efficiently separate free carriers but also maintain a high redox potential.