Highly efficient visible-light photocatalysis by Fe-substituted ZnO nanoparticles: Dual action on methylene blue degradation and microbial elimination

In this study Fe-substituted ZnO (Fe/ZnO) nanoparticles (NPs) are synthesized and utilized as an enhanced photocatalyst for the degradation of Methylene Blue (MB) and the inactivation of bacterial strains such as S.aureus and E.coli . The Fe/ZnO NPs were successfully synthesized using a sol-gel method assisted by combustion. Characterizations were performed using a range of analytical instruments, including Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM-EDX), Brunauer–Emmett–Teller (BET) surface area analysis, Thermogravimetric Analysis (TGA), Photoluminescence (PL), and X-ray Diffraction (XRD). Compared to pure ZnO (24 nm) and other dopants, the resulting Fe(0.5 %)-ZnOnanohybrid exhibited a smaller particle size (12 nm). The degradation efficiency of the synthesized nanohybrids was evaluated by monitoring the degradation of Methylene Blue (MB) in an aqueous solution under visible light exposure. The photocatalytic efficiency of the synthesized Fe/ZnOnanohybrid was significantly higher within 120 min under consistent conditions, including pH:10, catalyst loading (50 mg), and MB dye concentration (10 ppm). Additionally, the antibacterial effectiveness of the samples was evaluated against two pathogenic strains ( S.aureus and E.coli ) using the agar diffusion method. At a concentration of 800 µg/mL, the Fe/ZnOnanohybrid demonstrated the highest inhibition (1.2 mm) of S. aureus growth, indicating that Fe doping enhances ZnO's antibacterial properties. The enhanced photocatalytic and antibacterial activities are attributed to the reduced band gap, increased visible light absorption, and improved charge separation caused by Fe doping, which leads to a greater generation of reactive oxygen species.