Preparation and photocatalytic properties of carbon/carbon-doped TiO2 double-layer hollow microspheres

A carbon/carbon-doped titanium dioxide double-layer hollow microsphere (C/TiO 2 microsphere) photocatalyst was prepared by hydrolysis of thermal expendable microspheres (TEMs) and a TiO 2 sol–gel process. The thickness of the TiO 2 and carbon layers was controlled by the concentration of sulfuric acid used for hydrolyzing the TEMs. The photocatalytic activity of the samples was studied with rhodamine B as a target degradation product. The result showed that the photocatalytic activity was affected by the thickness of the carbon and TiO 2 layers significantly. The C/TiO 2 microspheres obtained with 65% H 2 SO 4 possessed the best photocatalytic activity. Compared with pure TiO 2 , the visible light absorption range of the C/TiO 2 microspheres was expanded to 643 nm; the specific surface area was more than five times of the pure TiO 2 ; the response intensity of photocurrent was ten times of the pure TiO 2 . The degradation rate of rhodamine B caused by the photocatalysis of the C/TiO 2 microspheres was 96% in 140 min, and kept 83% after three times of reuse. The C/TiO 2 microspheres were easy for recycling and showed great potential in wastewater treatment.