Visible-light induced hydrophilicity on nitrogen-substituted titanium dioxide films.

Nitrogen-substituted titanium dioxide thin films were found to undergo hydrophilic conversion under irradiation with visible light. The hydrophilicity was enhanced by increasing the degree of nitrogen substitution at oxygen sites. The water contact angle for the thin film with the greatest hydrophilicity, TiO1.9884N0.0116, changed from 20 degrees to 6 degrees following irradiation.