C/N-sensitized self-assembly of mesostructured TiO2 nanospheres with significantly enhanced photocatalytic activity

Uniformly carbonaceous and nitrogenous species sensitized TiO2 quantum dots (QDs, similar to 4 nm) were synthesized through an improved strategy employing an oleic acid and oleylamine system, and were further assembled into the mesoporous structure of C/N-TiO2 nanospheres via an emulsion-based bottom-up self-assembly (EBS). EBS not only transformed oil-soluble C/N-TiO2 QDs into water-soluble nanospheres, but also assembled them into mesostructures with an average diameter around 200 nm. The photocatalytic properties of the as-prepared C/N-TiO2 QDs and C/N-TiO2 nanospheres were evaluated by measuring the photodegradation of rhodamine B (RhB) under visible-light irradiation. Compared to C/N-TiO2 QDs and commercial product P25, the experimental results showed that the water miscible mesostructured C/N-TiO2 nanospheres with improved effective catalytic area and RhB adsorption, and a red shift of the absorption edge to the visible light region, possessed improved photocatalytic activity. The purpose of this study is to illustrate the importance of C/N-species sensitization and fundamental structural control in effecting the photodegradation property of TiO2-based catalysts.