Suppressed photoelectrochemistry at carbon-surface-modified mesoporous TiO2 films

Cellulose nano-whiskers or nanocrystals are used as a carbon source in a vacuum graphitisation process to surface-modify nano-TiO2 and influence its photoreactivity. In sharp contrast to bulk carbon-modified TiO2 materials, introducing cellulose in a controlled way, i.e., a layer-by-layer deposition process, allows thin film materials to be created with low graphite content, but with strongly suppressed responses to light. The effect is explained by highly effective surface recombination and demonstrated for the I3−/I− redox system in acetonitrile and for the photo-oxidation of acetate in aqueous media.