Light-induced interfacial charge redistribution in a BiOCl/Zn₃In₂S₆ heterojunction for H₂O₂ production and pollutant degradation

A BiOCl/ZIS heterojunction was constructed by ultrasound-assisted assembly. • Interfacial coupling induced directional redistribution of photocarriers. • 3-BZ efficiently degraded concentrated RhB, CR, and TC under visible light. • 3-BZ achieved efficient photocatalytic H₂O₂ production under visible light. • In situ XPS and DFT supported type-II electron transfer from ZIS to BiOCl. An ultrasound-assisted assembly route was used to construct a BiOCl/Zn₃In₂S₆ (ZIS) heterojunction for visible-light-driven pollutant degradation and H₂O₂ production. After 120 min of irradiation, the optimized composite degraded 99.59% of Rhodamine B (RhB, 600 mg/L), 99.82% of Congo red (CR, 200 mg/L), and 83.50% of Tetracycline (TC, 80 mg/L). In a separate O₂-saturated medium containing 10 vol% isopropanol, the H₂O₂ yield reached 5644 μmol g⁻¹ over the same period. In situ irradiated X-ray photoelectron spectroscopy showed that Bi 4 f, Cl 2p, and O 1 s shifted toward lower binding energies, whereas the ZIS-associated core levels shifted toward higher binding energies. These opposite changes indicate photoelectron enrichment in BiOCl and electron depletion in ZIS. Density functional theory calculations revealed a larger work function for BiOCl (6.72 eV) than for ZIS (5.33 eV), while the differential charge density confirmed interfacial electron redistribution. Together with the density-of-states and experimental band-edge results, these findings support a type-II pathway in which electrons migrate from the ZIS conduction band (CB) to the BiOCl CB, while holes transfer from the BiOCl valence band (VB) to the ZIS VB. The resulting carrier separation favors O₂ reduction toward H₂O₂ formation and promotes oxidative pollutant degradation. Download: Download high-res image (225KB) Download: Download full-size image