Improving Carbon‐Coated TiO 2 Films with a TiCl 4 Treatment for Photocatalytic Water Purification

By using a simple thermal decomposition route, carbon‐TiO 2 hybrid films have been synthesized from a catechol‐TiO 2 surface complex. The coated films display enhanced visible region absorption, owing to the thin (≈2 nm) layer of carbon encapsulating the TiO 2 . Although photocatalytically active under visible light alone, it is demonstrated that the activity of the carbon‐coated films can be improved further by a hydrolytic treatment with TiCl 4 , leading to the introduction of small TiO 2 particles (5–10 nm) and doping of chlorine into the structure. The combination of the carbon layer and TiCl 4 treatment gives increased photocatalytic performance for the photodegradation of dyes, phenolic pollutants and the reduction of toxic Cr VI to relatively benign Cr III . In addition, the carbon‐coated films show improved bactericidal activity under UV irradiation, and hence have been successfully tested against the most common types of pollutant present in potential drinking waters.