Photocatalytic Activities of TiO2 Coated on Different Semiconductive SiC Foam Supports.

Different semiconductive SiC foam supports were prepared by varying the sintering temperature and atmosphere, and with or without alkaline solution treatment and high temperature oxidation following a macromolecule pyrogenation combined with reaction bonding method. Nano-TiO₂ particles were immobilized onto these SiC foam supports by a composite sol–gel method. The phase, surface morphology, the type of conduction and the photocatalytic activity of the TiO₂–SiC composite photocatalysts were studied. The TiO₂ coated on p-type Si-free SiC support showed the highest photocatalytic efficiency in degradation of 4-aminobenzenesulfonic acid (4-ABS) in aqueous solution as compared to that coated on n-type SiC support and p-type SiC supports with residual Si or SiO₂ on the surface. The result showed that the TiO₂ coatings immobilized on p-type semiconductive SiC foam supports exhibited obviously higher photocatalytic activity in comparison to that coated on n-type SiC foam support. The p–n heterojunctions formed between the p-type SiC supports and n-type TiO₂ coatings might be able to account for the better charge separation and transfer as well as the photocatalytic activity of the TiO₂–SiC composite photocatalyst. [ABSTRACT FROM AUTHOR]