Sonochemical synthesis of ZnCo₂O₄/Ag₃PO₄ heterojunction photocatalysts for the degradation of organic pollutants and pathogens: a combined experimental and computational study

ZnCo₂O₄/Ag₃PO₄ heterostructure nanoparticles were prepared via a facile ultrasonic method and characterized using various techniques. The photocatalytic activity of ZnCo₂O₄/Ag₃PO₄ nanoparticles was investigated for the degradation of organic pollutants (methyl orange and bisphenol A) under visible-light irradiation. An enhanced photocatalytic efficiency was observed within 75 minutes compared with the individual constituents. A mechanism of the enhanced photocatalytic activity of the heterojunction is proposed based on density functional theory (DFT) calculations. The cytotoxicity of the ZnCo₂O₄/Ag₃PO₄ nanoparticles was tested against the breast cancer cell line (MCF-7), the human colorectal cancer cell line (HCT116) and the normal human foreskin fibroblast cell line (HFF). More cytotoxicity was observed against the fibroblast cell line. The antimicrobial and antifungal activities of the ZnCo₂O₄/Ag₃PO₄ nanoparticles were also examined against methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Pseudomonas aeruginosa (MDR-PA) and the yeast Candida albicans. It was observed that MDR-PA was more susceptible to ZnCo₂O₄/Ag₃PO₄ nanoparticles than MRSA and Candida albicans. Furthermore, the effect of the ZnCo₂O₄/Ag₃PO₄ nanoparticles on biofilm formation by MDR-PA, MRSA and Candida albicans was also studied. The results indicated that the inhibition of biofilm production by MDR-PA was higher than for MRSA and yeast under similar conditions.