Highly efficient and morphology dependent antibacterial activities of photocatalytic CuxO/ZnO nanocomposites

This study reports on morphology dependent antibacterial activities of CuxO/ZnO nanocomposites towards Escherichia coli. The CuxO/ZnO nanocomposites were formed by aqueous photoreduction of CuxO nanostructures on solution grown ZnO nanorods on Si substrates. By controlling the photoreduction time and temperature, various CuxO nanostructures including nanocubes, nanoclusters, nanospikes, and nanowebs were created as verified by scanning electron microscopy. X-ray diffraction analysis reveals the good crystallinity of the ZnO nanorods. X-ray photoelectron spectroscopy confirms the successful deposition of CuO and Cu2O nanostructures on the nanorods. Antibacterial tests were performed in dark and under low-intensity blue-light irradiation. The nanoweb sample has an antibacterial efficiency of 95.8% for 10 min in dark and the nanospike sample has an efficiency of 99.5% for 10 min under light. For the nanospike sample, remarkable bacterial survival ratios of 3 × 10–4 and 10–5 in dark and under light both for a 60 min reaction time, respectively, have been achieved. The excellent antibacterial performance is attributed to combined effects of mechanical piercing of ZnO nanorods, release of Zn2+, Cu2+, and Cu+ ions, and effective generation of reactive oxygen species due to charge separation.