Synergy of Z-scheme heterostructure with interfacial S−O bonding in In2S3/BiOBr for efficient tetracycline hydrochloride degradation and Cr(VI) reduction

High-efficiency interfacial charge transfer is the key to achieve better spatial carrier separation, and thus to develop advanced heterogeneous photocatalysts for environmental remediation. However, It still remains a great challenge to design and exploit the effective charge transfer scheme. Herein, a novel Z-scheme In2S3/BiOBr with S−O covalent bonding was prepared by hydrothermal and subsequent thermal annealing methods. The obtained photocatalysts were systematically characterized and used for tetracycline hydrochloride degradation and Cr(VI) reduction in aqueous solution. As a result, the optimized In2S3/BiOBr heterostructure (IS/BOB-39) exhibited superior photocatalytic activities for tetracycline hydrochloride degradation and Cr(VI) reduction under simulated solar light irradiation compared with individual materials. The Z-scheme transfer mechanism was corroborated by trapping experiments, ESR and XPS analysis, which provided an effective transfer pathway for spatial separation of carriers. Moreover, the formation of chemical S−O bond between In2S3 and BiOBr, which acted as a specific bridge to expediently transmit interfacial electrons, showed a synergistic effect with Z-scheme transfer model on the significantly enhanced photocatalytic performance. In addition, the In2S3/BiOBr heterojunction presented excellent cycle stability, resulting from the tight heterointerface. This work provides a promising approach to design and fabricate high effect Z-scheme heterojunction in wastewater treatment.