Superior performance of plasma treated water as an anodizing electrolyte for producing nanoporous titanium dioxide nanotubes

An environmentally friendly electrolyte for the synthesis of titanium dioxide nanotubes by anodization is presented. Plasma treatment of de-ionized water produces some important reactive species such as nitrate and hydrogen peroxide. This plasma-treated water serves as an efficient electrolyte in the formation of titanium dioxide nanotubes during anodization. In order to further understand the roles of nitrate and hydrogen peroxide, titanium foil was anodized in plasma treated water containing nitrate or/and hydrogen peroxide as well as in its equivalent solution made by adding nitric acid and/or hydrogen peroxide to water. It was found that the plasma treated water containing both nitrate and hydrogen peroxide produced more uniform arrays of highly crystalline titanium dioxide nanotubes than produced in the aqueous solution made with nitric acid and hydrogen peroxide.