Quercetin-mediated 3-D hierarchical BiOI-Q and BiOI-Q-Ag nanostructures with enhanced photodegradation efficiency

The nanostructured BiOI-Q-Ag composites were prepared by a quercetin-assisted hydrolysis route under varying concentrations of Ag. The samples were examined under microscopic and spectroscopic investigations, which revealed that the Ag nanoparticles (NPs) were efficiently loaded on the 3D BiOI-Q nanoflowers, and a higher density was observed with increasing amount of Ag. The photocatalytic activities of the as-synthesized BiOI-Q, BiOI-Q-Ag (1), BiOI-Q-Ag (2), and BiOI-Q-Ag (3) samples were examined for the methyl orange degradation (MO) and antibacterial activity against four different bacteria i.e. Bacillus pumilus, Acinetobacter baumanni, Staphylococcus aureus, and Pseudomonas aeruginosa under visible light irradiation (VLI). The BiOI-Q-Ag composites showed improved photocatalytic performances over BiOI-Q signifying the important role of the Ag amount and the optimized ratio was obtained at BiOI-Q-Ag (2). The enhancement in the visible light photocatalytic performance of the BiOI-Q-Ag composites could be attributed to the effective separation of the photogenerated electron-hole (e--h+) pairs at the multiple interfaces developed among BiOI, Ag and the quercetin, which facilitated the effective charge transfer. The trapping experiment suggested that the h+, .OH, and . O2− were the dominant active species in the photodegradation process. The electrochemical studies showed that the recombination of the photoinduced charges in the BiOI-Q-Ag (2) composite was inhibited strongly as compared to the BiOI-Q sample. The photocatalytic activity of the BiOI-Q-Ag (2) composite was maintained for the cycling experiments.