Dual electric field and defect engineering induced multi-channel electron transfer for boosting photocatalytic hydrogen production on Cu-doped ZnMoO/ZnInS heterojunction.

Serious recombination of photogenerated carriers is the bottleneck problem of achieving high-performance photocatalytic reaction. A high efficient Cu-doped ZnMoO/ZnInS (CZMOZIS) heterojunction was synthesized by hydrothermal method. The CZMOZIS heterostructure achieved hydrogen production of 11637.5 µmol g within 5 h, which was 9.7 times higher than that of pure ZnInS. Comprehensive characterization and theoretical calculation demonstrated that the CZMOZIS composites exhibited broad light absorption, an increased specific surface area and an optimized Gibbs free energy. The presence of oxygen vacancies in CZMOZIS composites was confirmed by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy, revealing the formation of defect levels below the conduction band (CB) of ZnMoO. Kelvin probe force microscopy (KPFM) and Zeta potential demonstrated that the intrinsic electric field (IEF) of the CZMOZIS heterojunction was enhanced, which may be attributed to the generation of polarization electric field (PEF). The double electric field provided a robust driving force for the photogenerated carrier migration and separation. The electrons in the CB and defect levels of Cu-ZnMoO could be coupled with the holes of ZnInS, thereby forming a multi-channel electron transfer. This work provides a theoretical support for promoting charge transfer to improve photocatalytic performance by dual electric field and defect engineering.