Hydrothermally Synthesized CuO Powders for Photocatalytic Inactivation of Bacteria

Various morphologies of monoclinic CuO powders were synthesized by hydrothermal treatment of copper nitrate, copper acetate or copper sulfate. The synthesized samples were characterized by scanning electron microscopy, X-ray diffractometry, the Fourier transform infrared spectroscopy, and diffuse reflectance spectrophotometry. Antibacterial activity of the samples was studied against Escherichia coli bacteria in dark and under visible light irradiation. Although the different precursors yielded the same band gap energies (approximate to 1.6eV) for the synthesized CuO samples, they resulted in various morphologies (hierarchy of stabilized micro/nanostructures), specific surface areas, concentrations of OH-surface groups, and visible light photocatalytic performances. The CuO nanorods synthesized from nitrate hydrothermal bath not only exhibited a considerable effective surface area, but also showed the highest concentration of absorbed OH-groups and subsequently, the strongest (photo)catalytic antibacterial properties and (approximate to 37 and 94% inactivation of the bacteria in dark and under visible light irradiation, respectively).