Optimizing visible light absorption, exciton dissociation, and charge transfer through the interaction of...

Bulk heterojunctions, formed by blends of donor and acceptor materials, are attractive for developing efficient photocatalysts due to their tunable optical and electrical properties. However, their potential for enhancing organic wastewater treatment through adjustable light absorption bands and intensities remains largely unexploited. In this work, a novel kaolin (KA) based ternary heterojunction photocatalyst PBT1-C:IDT8CN-M:PDI-V/KA (PIV/KA) with strong absorption capability in the spectral range of 470-800 nm was synthesized through the clever combination of donor and acceptor materials and the construction of Förster resonance energy transfer (FRET) between IDT8CN-M (I) and PDI-V (V). PIV/KA exhibits high photocatalytic performance, degrading 99.8 % of sodium ethyl xanthate (SEX) within 10 min, and achieving high degradation rates for the other four common xanthates. This excellent performance is attributed to the complementary light absorption of PBT1-C (P), I, and V, which broadens the visible light harvesting ability of PIV and promotes exciton generation. Meanwhile, the FRET from V to I alters the exciton jump mode and broadens the pathway of exciton dissociation in the ternary system, facilitating exciton dissociation and charge transport. Finally, thanks to the dispersion stabilization of KA, PIV/KA can efficiently generate a large number of strong oxidizing radicals (∙O₂^- and ∙OH, etc.) to degrade SEX under visible light irradiation. This study provides theoretical guidance for constructing efficient bulk heterojunction photocatalysts to treat SEX in mineral processing wastewater.