The sol–gel process is used to prepare photocatalytic coatings with antibacterial properties. Also, doping with metallic or non-metallic elements has an impact on the antibacterial and photocatalytic activity of these coatings. Although there are many studies in this field, the effect of co-doping with Cu and N and their concentrations on the antibacterial properties of TiO2 coatings against the E. coli and S. aureus bacteria has not been studied. In the present investigation, the sol–gel method was employed to deposit both undoped and Cu-N co-doped TiO2 photocatalytic coatings on glass surface, which are expected to degrade bacterial and chemical contaminants in water while exposed to visible sunlight wavelengths. Before the coating process, an appropriate heat treatment was applied on the samples and the quality of coatings, band gap energy, and also photocatalytic and antibacterial properties were evaluated. Results showed that, in the presence of dopants, the band gap become narrower and the absorption spectrum is transferred from the ultraviolet to the visible light range. Also, it was demonstrated that, under the visible light radiation, all of the co-doped samples show higher photocatalytic activity than the undoped ones. Meanwhile, the antibacterial characteristics of TiO2 coatings was enhanced by increasing the dopant concentration when exposing to sunlight.
