Impact of copper doping in NiO thin films on their structure, morphology, and antibacterial activity against Escherichia Coli

Abstract Impact of Cu doping on the structure, morphology, and antibacterial activity of NiO thin films has been investigated for a broad range of Cu/Ni ratios (0.1–25%). These thin films were synthesized on pre-heated glass substrates using indigenous spray pyrolysis setup. The structural analysis via X-ray diffraction technique reveals that all the thin films are of polycrystalline nature with cubic structure. All the diffraction peaks shift towards lower angle on an increase in the Cu/Ni ratio. Texture coefficient and stacking fault probability were determined by Harris analysis and Warren – Warekois formula, respectively. Crystallite size and lattice strain were valued by means of Williamson – Hall analysis, size-strain plots, Scherer and Wilson formulae. The value of crystallite size shows a decreasing trend while lattice strain increases on increasing the Cu/Ni ratio. SEM micrographs of the thin films reveal that surface morphology consists of pores, and the density of these pores decreases as the Cu/Ni ratio increases. The characteristic absorption bands exhibited by FTIR spectra of un-doped NiO and NiO:Cu thin films recorded in the range 4000–450 cm−1 were identified. Pure NiO thin film is found to be a very good antibacterial agent against the Escherichia Coli bacteria. However, its antibacterial ability gradually decreases on doping with 0.1–25% Cu.