Reduced graphene oxide/TiO2/NiFe2O4 nanocomposite as a stable photocatalyst and strong antibacterial agent

Abstract In this work, (rGO)/TiO2/NiFe2O4 or GTN nanocomposites were prepared as novel photocatalysts and strong antibacterial agents using a facile, cheap, and scalable hydrothermal method. To prepare the nanocomposites, different mass ratios of rGO:TiO2:NiFe2O4 were chosen as 1:1:1, 2:1:1, 3:1:1, and 4:1:1, and they called as GTN111, GTN211, GTN311, and GTN411, respectively. The photocatalytic results showed that 0.1 mg.mL− 1 of composite degrades 95% and 89% of 20 ppm methylene blue (MB) under UV and visible light irradiation, respectively. Under visible exposure, the first-order rate constant was calculated as 90×10− 3 min− 1 for GTN211 nanocomposite. It was found that the holes and OH radical species play the main role in degradation of MB. The antibacterial activity of the best photocatalyst, i.e., GTN211, against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was also investigated. The minimum inhibitory concentration of GTN211 was measured as 1 mg.mL− 1 for E. coli and S. aureus. The value of minimum bactericidal concentration of GTN211 was meaured as 0.8 and 1 mg.mL− 1 for E. coli and S. aureus, respectively.