Diatom-templated TiO_2 with enhanced photocatalytic activity: biomimetics of photonic crystals

摘要

The siliceous frustules with sophisticated optical structure endow diatoms with superior solar light-harvesting abilities for effective photosynthesis. The preserved frustules of diatom (Cocconeis placentula) cells, as biophotonic crystals, were thus employed as both hard templates and silicon resources to synthesize TiO_2 photocatalyst. Characterizations by a combination of physicochemical techniques proved that the bio-inspired sample is TiO_2-coated SiO_2 with biogenic C self-doped in. It was found that the synthesized composites exhibited similar morphologies to the original diatom templates. In comparison with commercial Degussa P25 TiO_2, the C-doped TiO_2/SiO_2 catalyst exhibited more light absorption in the visible region and higher photocatalytic efficiency for photodegradation of rhodamine B under visible light due to the biomorphic hierarchical structures, TiO_2 coating and C-doping.