Visible light active photocatalytic C-doped titanium dioxide films deposited via reactive pulsed DC magnetron co-sputtering: Properties and photocatalytic activity

Doping of TiO2 with carbon is known to be an efficient method of enhancing visible light photocatalytic activity. The present work describes the deposition of carbon-doped titania coatings deposited by reactive magnetron co-sputtering of Ti and C targets. Undoped titania coatings were produced under similar deposition conditions for comparison purposes. Following deposition, all coatings were annealed in air at 873 K for 30 min to develop the required crystalline structure; and then analysed with EDS, XRD, AFM, XPS and UV-visible spectrophotometry. A number of tests, including methylene blue and stearic acid decomposition tests, and photo-induced hydrophilicity measurements, were employed for the assessment of the photocatalytic properties of the C-doped and un-doped titanium dioxide coatings under UV and visible light irradiation. It was found that carbon-doped titania coatings significantly outperformed undoped titania when using both visible and UV irradiation. Similar trends were observed for other properties. While excessive carbon doping has been shown to have a negative effect on the photocatalytic properties of the titanium dioxide, overall, carbon doping via reactive co-sputtering has been confirmed as an efficient method of photocatalytic property enhancement. This is due to a narrowing of the bandgap and to extended lifetimes of the photo-generated charge carriers.