Enhanced visible-light-driven photocatalytic degradation via in-situ AIS/ZIS high-low junctions

The I-III-VI QDs Ag-In-S (AIS) exhibits excellent properties in photocatalysis because of the adjustable band gap, wide light absorption range, and multiple active sites. Introducing homologous or heterogeneous ions not only derives the composition into quaternary/ quinary quantum dots but also generates new sulfide QDs to form composites, which is an effective strategy to promote photoactivity. In this work, we in-situ synthesized the AIS/ZIS (AgIn₅S₈/Zn₄In₂S₇) composite photocatalyst by introducing Zn²⁺ and changing the reaction temperature. We found that the composite photocatalyst could efficiently photodegrade larger concentrations of RhB than that of the previous reports. The superior photocatalytic activity was due to the formation of the type I high-low junction, which could effectively separate carriers. The photoelectrons on the CB of AIS reacted with dissolved oxygen to produce strongly oxidative O₂^-, which degraded RhB into intermediates and eventually into CO₂ and H₂O. This work not only reports an excellent photocatalyst but also offers new ideas on the design and manufacture of highly efficient high-low junction photocatalysts.