Synergistic effect of strong interfacial interaction and robust internal electric field on Mn-modified CdS/ZnIn2S4 heterostructure for boosting photocatalytic performance

Heterojunction photocatalysts have demonstrated significant efficacy in degrading organic pollutants. However, charge transfer efficiency remains suboptimal, primarily due to weak interfacial interactions and an insufficient internal electric field (IEF). Herein, Mn-modified CdS (MCS-0.25) was synthesized on the surface of flower-like ZnIn 2 S 4 (ZIS) to create MCS-0.25/ZIS heterojunction photocatalysts. Experimental results and density functional theory (DFT) calculations confirmed that the matching of nano/microstructures and the bridging of shared sulfur atoms at the interface enhance interfacial interactions and improve the adsorption and activation capacity of O 2 , thereby creating favorable external conditions. The modification with Mn reduces the activation barrier for electron migration, resulting in the formation of a robust IEF within the MCS-0.25/ZIS and providing a significant intrinsic driving force. The flower-like morphology and pore structure of MCS-0.25/ZIS facilitate three-phase contact and mass transfer. Consequently, a rapid and nearly complete degradation of high concentrations of tetracycline (99.61 %) is achieved over the 60MCS-0.25/ZIS heterostructure, with a rate constant of 0.07326 min −1 , surpassing most reported CdS and ZIS based photocatalysts. Furthermore, the optimized heterostructure exhibited remarkable recycling stability, environmental tolerance, photocorrosion resistance, and universality for applications in wastewater purification. This work establishes a design model for deliberate modulation of charge transfer at the heterointerface.