The Effect of Light Irradiation on the Antibacterial Activity of Copper Oxide Surface

Copper is an antibacterial material. The surface of copper exposed to the atmosphere is covered with copper oxides (Cu2O and CuO), and copper oxides exhibit photocatalytic activity under visible light irradiation. In this study, we investigated the effect of the light irradiation on the antibacterial activity of Cu2O and CuO surface layer. Antibacterial tests were carried out on the basis of ISO 22196 using Escherichia coli (NBRC 3972) under the silica lamp irradiation or in the dark. Photocatalytic activities of Cu2O and CuO were measured by methyl orange decomposition tests and electrochemical open-circuit potential measurements. CuO exhibited photocatalytic activity under the light irradiation, while Cu2O was less active. Photocatalytic activity activated by the light irradiation increased the amount of hydrogen peroxide, super oxide radical and hydroxyl radical, and as the result, the antibacterial activity of CuO increased.