Direct dual CaIn2S4/Bi2WO6 semiconductor nanocomposites with efficient inter-cross-sectional charge carrier transfer for enhanced visible light photocatalysis

A visible light-responsive redox-mediator-free calcium indium sulfide (CaIn2S4) and bismuth tungstate (Bi2WO6)–based direct dual semiconductor nanocomposites were prepared by combination of hydrothermal and wetness impregnation methods. The results substantiated the formation of CaIn2S4 marigold flowers, the flower-like structure of the Bi2WO6, and CaIn2S4/Bi2WO6 nanocomposites. UV–Vis-DRS analysis confirmed that visible light response of Bi2WO6 was considerably enhanced after combining with CaIn2S4. The inter-cross-sectional charge carrier transfer during photocatalysis using synthesized catalysts was studied by determining the band position of Bi2WO6 and CaIn2S4, and photoluminescence analysis. The adsorption of rhodamine B (RhB) dye study revealed that after coupling with CaIn2S4, the adsorption capacity of Bi2WO6 was significantly improved. For 15%-CaIn2S4/Bi2WO6, 38% of RhB dye was adsorbed, whereas it was 27% for bare Bi2WO6. The 15%-CaIn2S4/Bi2WO6 nanocomposite showed higher percentage degradation for RhB (82%) dye as compared to the other percentage loaded composites, bare Bi2WO6 (59%) and CaIn2S4 (72%). Photoluminescence results revealed that photo-generated electron–hole pair recombination rate was drastically suppressed after coupling with CaIn2S4 which may be presumed to inter-cross-sectional transfer of photo-generated charge carriers. The synergic effect of enhanced adsorption capacity and efficient separation of electron–hole pairs were accountable for the enhanced photodegradation efficiency under visible light.