Effects of dopants on multiple functionalities of TiO 2 −coated TC4 alloys

In this study, a TiO 2 , Ag−doped or Cu−doped TiO 2 film was deposited on a TC4 alloy, and the effects of the dopants (i.e., Ag and Cu) on the photoelectrochemical response, biofilm suppression as well as corrosion resistance of the TiO 2 −coated alloy were systematically investigated. It can be found that the Ag doping in TiO 2 can bring about the increased concentration of oxygen defects, thereby elevating the charge carrier density and enhancing the photoelectric and corrosion current responses, which can promote the photoelectrochemical response but concurrently deteriorate the corrosion resistance of the TC4 alloy substrate. Notably, a drastic decrease in the crystallite size of TiO 2 can be induced by Cu doping and an almost amorphous state is achieved, which is accompanied by the reduction in the charge carrier mobility as well as photoelectric densities. Nevertheless, both the Ag− and Cu−doped TiO 2 films exhibit pronounced corrosion resistance and biofilm suppression activity. Accordingly, the photocurrent response may be influenced by differences in charge-carrier density and mobility, corrosion resistance as well as crystallite size of the TiO 2 film.