Direct transformation of metallic copper to copper nanostructures by simple alcohol thermal treatment and their photoactivity

A novel technique based on alcohol thermal treatment (ATT) was attempted to prepare copper nanostructures in a large scale. ATT provided copper sheets with high energy, resulting in the reconstruction of atoms into different atomic configurations and direct transformation of metallic copper to copper nanostructures. Copper nanostructures including nanobelts, nanowires and nanoparticles can be fabricated by adjusting the time of ATT. The ultraviolet visible diffuse reflectance spectra show ATT substantially enhanced the visible light (VL) absorbance of Cu nanostructures and Cu nanowire arrays gave the most efficient light harvesting in all of the samples. Photoelectrochemical and antibacterial experiments were carried out to investigate the photoactivity of different copper nanostructures. The results show the nanostructured surfaces by ATT significantly improved the photoactivity of copper sheets, among which copper nanowires demonstrated the highest photoactivity in bactericidal and photovoltaic effects since they completely inactivated 5 log of Escherichia coli K-12 within 1.5 h and produced 35 mV photovoltage under visible irradiation. The order of photoactive bactericidal effects for different nanostructured surfaces was also determined as Cu nanowires > Cu nanobelts > Cu nanoparticles > untreated Cu sheet, which was in accordance with that of VL absorbance and photovoltaic effects.