Zinc-doped iron oxide nanostructures for enhanced photocatalytic and antimicrobial applications

A simple, cost-effective method of two-step anodization is used to prepare environmentally benign zinc-doped iron oxide nanostructures for photocatalytic and antimicrobial applications. The effect of zinc doping on the structure and morphology of iron oxide nanostructure is analysed with the help of X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy. A detailed analysis of the changes in the binding energy positions of Fe 2p, O 1s, Zn 2p and valence band maximum with variation in doping concentration is carried out with X-ray photoelectron spectroscopy. A combined analysis of valence band X-ray photoelectron spectra and optical reflectance spectra indicates a shift in Fermi level characteristic to a conversion from n-type in pure α-Fe2O3 to p-type in 5-s zinc-doped α-Fe2O3. The room-temperature electrical conductivity of the doped is improved by five orders compared to the undoped nanostructures. The zinc-doped iron oxide nanostructures with p-type conductivity are found to show high photocatalytic degradation efficiency for the organic dye methylene blue. Significant antimicrobial activity is observed with the nanostructures for the microbes Pseudomonas aeruginosa, Bacillus subtilis and E. coli.