Dual-Z-scheme Co3O4/CoO-CNNS heterojunction for facilitating charge transport toward improving photocatalytic hydrogen generation

Photocatalysts with double Z-scheme mechanism can effectively promote the separation and transmission of photo-induced carriers. In this work, a novel Co3O4/CoO-CNNS ternary composite photocatalyst was prepared by electrostatic self-assembly of flower-like Co3O4/CoO composites supported on g-C3N4 nanosheets (CNNS), which was expected to provide more active sites for photocatalytic hydrogen evolution. Density functional theory (DFT) calculations, surface photovoltage (SPV) and electron spin resonance (ESR) measurements demonstrate that Co3O4/CoO-CNNS ternary composite followed a double Z-scheme charge transfer mechanism, resulting in an improvement of separation rate and redox capacity of the carrier. In addition, 15 %Co1Co2-CN exhibits a hydrogen evolution performance of 4050.60 µmol·g−1·h−1 during the photocatalytic water-splitting. This work offers new insights for the design and development of photocatalysts with double Z-scheme charge transfer mechanism.