Lattice-oxygen doping boosts ZnIn2S4 as a high-performance photocatalyst for CO2 reduction

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Heteroatoms can be doped into the crystal lattice to introduce defects by physical or chemical methods, which can adjust the band structure of the photocatalyst, and ultimately affect the photocatalytic performance of the photocatalyst. Herein, ZnIn2S4 (ZIS) nanoflowers with high content lattice-O doping were synthesized by one-pot ion-exchange method from solid ZnO source. The peaks of lattice-O (531.4 eV) and O vacancies (530.0 eV) presence in XPS spectra support the existence of lattice-O in the ZnIn2S4 (ZIS) nanoflowers. Numerous 2D ultrathin nanosheets assembled ZIS nanoflowers would resulted into hierarchical structure with high surface and mesoporous structure. With optimum Zn/In ratio in the obtained materials, ZIS (1:3:9) show enhanced CO2 to CO conversion activity(1038.4 μmol·g−1·h−1) and a low CH4-evolving rate of 4.9 μmol·g−1·h−1 under visible light irradiation. The obtained ZIS (1:3:9) material can significantly promote photogenerated charge separation, accelerate transfer of photogenerated electrons, delay the recombination of electrons and holes. This work opens up a new way for element doping and careful construction of heterojunctions to improve photocatalytic performance by improving photogenerated charge and hole separation and regulating band structure.