Band gap tailoring of cauliflower-shaped CuO nanostructures by Zn doping for antibacterial applications.

Transition metal oxide nanostructures are well known as attractive multi-functional nanomaterials and are among the most promising industrial materials for different science and technology applications. The present study, describes the optical, structural, and antibacterial properties of undoped and Zn-doped CuO nanostructures synthesised by a simple low-cost sol-gel technique. The synthesised nanostructures exhibited a monoclinic CuO structure as confirmed by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy. Various Zn doping of CuO nanostructures tuned their optical, structural, morphological, and antibacterial properties. Field emission scanning electron microscopy confirmed the formation of bunched cauliflower-shaped nanostructures after Zn doping. X-ray photoelectron spectroscopy was used to study the chemical state of CuO doped with Zn and dynamic light scattering measured the hydrodynamic size of the samples. Zn-doped CuO samples exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with a change in antibacterial behaviour compared to pure CuO structures. This study demonstrated the potential of using a simple synthesis methodology to produce tuneable nanostructures for multi-functional applications. Schematic mechanism of antibacterial activities of Cauliflower shaped CuO nanostructures doped with Zn with its chemical states. Image 1 • Pure and CuO:Zn nanostructures were synthesised by a simple low cost sol–gel technique. • Cauliflower shaped nanostructures formed after doping with Zn. • Optical tuneable nanostructures obtained for multi-functional applications. • Zn doped CuO samples exhibit excellent antimicrobial activities. [ABSTRACT FROM AUTHOR]