Cascaded BiS bridges and Ti-VS vacancy restore centers trigger parallel dual S-scheme exciton highways for ultrafast photocatalytic redox

The performance of photocatalysts is often limited by charge recombination and sluggish kinetics at heterojunction interfaces. This study develops a multi-strategy interfacial modulation approach by constructing Bi S covalent bonds at the BiVO 4 /Mn 0.5 Cd 0.5 S(MCS) interface to serve as electron transport “bridges”, while simultaneously filling sulfur vacancies (V S ) in MCS with Ti atoms to eliminate recombination centers. This dual optimization of interfacial charge dynamics is realized in a BiVO 4 /MCS/TiO 2 (BMT) ternary system. The design facilitates an efficient dual S-scheme heterojunction that, driven by an interfacial built-in electric field, enables highly efficient separation of photogenerated carriers while maximizing redox capability. Under visible-light irradiation, the composite achieves a degradation rate of 89.51% for norfloxacin within 30 min, along with excellent cycling stability. Combined spectroscopic analysis and theoretical calculations confirm that the Bi S bonds significantly reduce the interfacial charge-transfer barrier, while the Ti-V S structure effectively suppresses carrier recombination. The synergy between these two mechanisms is key to constructing an efficient S-scheme charge-transfer pathway. This work provides a clear strategy for designing high-performance photocatalytic systems through the cooperative integration of interfacial bonding and defect engineering. We developed a TiO 2 /Mn 0.5 Cd 0.5 S/BiVO 4 ternary system with dual interfacial modulation using Bi S covalent bonds as electron bridges and Ti filling of sulfur vacancies to construct a dual S-scheme heterojunction that suppresses charge recombination and enhances redox capacity. This synergy enables efficient norfloxacin degradation and stability under visible light. Download: Download high-res image (139KB) Download: Download full-size image