Role of the crystallite phase of TiO2 in graphene/TiO2 photocatalysis

Using chemisorption followed by annealing at different temperatures, TiO2 with different phases (anatase, rutile and mixed anatase/rutile) have been successfully assembled onto graphene sheet. The corresponding UV and visible induced photoactivities were evaluated using sensitized methyl orange and non-sensitized benzoic acid degradation as a probe reaction. The photocatalytic activities of TiO2 could be enhanced after assembled with graphene under UV and visible light irradiation both. However, Due to different charge transfer mechanism in UV and visible light irradiation system, the different crystallite phases of TiO2 acted different roles, hence displayed hierarchical enhancement phenomenon.