An S-scheme photocatalyst constructed by modifying SnIn4S8 nanosheets on AgVO3 nanorods for enhanced photocatalytic performance

Abstract

Composite photocatalyst have garnered considerable attention in the field of environmental remediation. In this study, we synthesized a one-dimensional (1D) core/shell AgVO₃@SnIn₄S₈ (AS) heterojunction photocatalyst by in situ growing SnIn₄S₈ nanosheets on AgVO₃ nanorods utilizing a straightforward solvothermal approach. The resultant AS composite demonstrates exceptional photocatalytic efficiency in both degrading methyl orange (MO) and reducing Cr(VI) pollutants. The optimized AS-0.1 heterostructure is particularly noteworthy, achieving almost complete MO degradation (99.7 %) within just 15 min and effectively reducing Cr(VI) 99.4 % within 75 min. The reaction rate constant k for MO degradation by the AS-0.1 sample is 0.3654 min⁻¹ , which is 8.2 times higher than that of SnIn₄S₈ (0.0446 min⁻¹) and 609 times greater than that of AgVO₃ (0.0006 min⁻¹). Similarly, the degradation constant k for Cr(VI) reduction by AS-0.1 is 0.0656 min⁻¹ , surpassing that of SnIn₄S₈ by 5.2 times (0.0127 min⁻¹) and AgVO₃ (0.0003 min⁻¹) by 218.7 times. This significant enhancement in photocatalytic activity is primarily attributed to the increased number of active sites and the efficient S-scheme charge transfer mechanism, which is facilitated by the built-in electric field within the AS heterostructure. The S-scheme mechanism facilitates the efficient migration of photogenerated charge, and endows photoexcited electrons and holes with high redox capacity, thereby accelerating the photocatalytic reactions. Furthermore, the recovered samples retain their photocatalytic degradation performance after five consecutive experimental cycles, suggesting their excellent durability. This study is expected to motivate the rational design and fabrication of efficient composite photocatalysts, offering innovative solutions to water pollution challenges.