Fabrication of novel ternary dual S-scheme ZnFe2O4/Ag3PO4/ZnIn2S4 photocatalyst with enhanced visible light-driven RhB degradation

This work synthesized a ternary dual S-scheme photocatalyst ZnIn2S4/Ag3PO4/ZnFe2O4 by co-modifying Ag3PO4 with ZnFe2O4 and ZnIn2S4 by facile co-precipitation method. XRD outcome established the formation of bare Ag3PO4, ZnIn2S4, and ZnFe2O4, and ZnIn2S4/Ag3PO4/ZnFe2O4 was shown to be pure since peaks matching these semiconductors appeared. These findings were further supported by the FTIR and XPS analyses, which revealed the shift in structural characteristics. UV–Vis spectroscopy showed a broader absorption spectrum of the nanocomposite and pointed out that it might be used as a photocatalyst in direct sunshine. Shorter charge transfer resistance and poor recombination rate of charge carriers are shown by a smaller radius in the EIS Nyquist plot and a less intense PL spectrum of ternary composite, respectively. Under simulated solar radiations, the photocatalytic performance of the ZnIn2S4/Ag3PO4/ZnFe2O4 (ZIS/SP/ZIS) nanocomposite (99.8 %) was the highest against RhB decolorization when compared to pure ZnIn2S4 (ZIS) (33.3 %), Ag3PO4 (SP) (19.6 %), ZnFe2O4 (ZF) (20.1 %) and binary Ag3PO4/ZnFe2O4 (SP/ZF) (55.4 %) nanocomposite. However, COD proved that complete mineralization took longer and took 240 min. Experiments on scavenging have shown that the radicals •O2−, h+, and •OH are created and influence RhB degradation in order: O2− > OH > h+. ESR experiment supported the scavenging study results. Out of two main schematic models used to depict the photocatalytic reaction mechanism, the S-scheme can effectively explain boosted light absorption, charge carrier separation, the synergistic effect of the components, and improved photocatalytic performance. Facile magnetic separation and photostability were observed as photocatalysts retained 90.8 % degradation efficiency after four reuse cycles.