Preparation and characterization of TiO2/carbon composite thin films with enhanced photocatalytic activity

Composite TiO2/carbon thin films prepared by physical vapor deposition techniques on fused silica substrates show enhanced photocatalytic activity towards decomposition of methanol to CO2 and water, as compared to pure TiO2 films of similar thickness. Raman and XRD measurements confirm that annealed TiO2 films exhibit anatase structure while the carbon layer becomes graphitic. Characteristic for the composite films is an enhanced optical absorption in the visible range. The presence of the carbon film causes a shift of the TiO2 absorption edge and modifies its grain size to be smaller. We hypothesize that the observed enhancement of photocatalytic activity is due to synergy effects at the carbon/TiO2 interface, resulting in smaller titania crystallite size and anisotropic charge carrier transport, which in turn reduces their recombination probability.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (194 K)Download as PowerPoint slideResearch highlights▶ Photocatalytic oxidation of methanol on composite (C + TiO2) and pure TiO2 film. ▶ Composite films show an enhanced photoactivity than pure TiO2. ▶ Enhancement is due to synergy effect of carbon at the TiO2 nanocrystals interface. ▶ The effect restricts crystal growth of TiO2 and contributes to charge separation.