Hierarchical core-shell heterostructures of ZnIn2S4 nanosheets on electrospun In2O3 nanofibers with highly enhanced photocatalytic activity

Well-designed heterostructure semiconductor photocatalysts can improve the activity of photocatalytic reactions. In this work, we constructed a series of hierarchical ZnIn2S4/In2O3 heterostructures by growing ultrathin two-dimensional ZnIn2S4 nanosheets onto one-dimensional In2O3 electrospun nanofibers and used them as photocatalysts for the efficient photoreduction of toxic Cr(VI). This structural design increased the specific surface area, promoted the separation of photogenerated electrons and holes, and provided more active sites for the catalytic reactions. Under visible light irradiation, the optimized ZnIn2S4/In2O3 photocatalyst showed the highest photocatalytic performance with 100% reduction efficiency for Cr(VI) (50 mg/L) within 90 min, which is much higher than pure In2O3 and ZnIn2S4. Additionally, the recycling tests and X-ray diffraction (XRD) characterization indicated the stability of the ZnIn2S4/In2O3 photocatalyst, making it a promising candidate for environmental remediation applications. Finally, the two active species (e and O-2(-)) participating in the photoreduction process were determined via trapping experiments and electron spin resonance (ESR) spectroscopy. Finally, a possible mechanism for the ZnIn2S4/In2O3 heterojunction photocatalytic system was carefully determined.