Full mineralization of toluene by photocatalytic degradation with porous TiO2/SiC nanocomposite film

Photocatalysis is a promising technique to fully decompose toluene and other volatile organic compounds (VOCs). In this work, porous TiO2/SiC nanocomposite films were synthesized by ball-milling and screen printing technique. Their photocatalytic properties in the degradation of toluene were carried out in a self-made reactor system. It was found that, in dry condition, the mineralization ratio of toluene by TiO2/SiC nanocomposite increased to 1.61 times comparing with pure TiO2. What is more, when TiO2/SiC nanocomposite was applied in humid condition the mineralization ratio increased to nearly fivefold that of pure TiO2 in dry, up to 100% of mineralization. These results were smoothly explained by the synergistic effect of TiO2–SiC heterojunction and the interaction between water and TiO2 (SiC). Due to the special staggered type energy band structure heterojunction, the photogenerated electrons gathered on TiO2 and holes enriched on SiC. Both of which participated in the degradation of toluene in more efficient ways and owing to the hydrophilicity of TiO2 and hydrophobicity of SiC, the mineralization capacity of photogenerated electrons and holes was largely promoted. The final results indicated that the hydrophilicity (hydrophobicity) of photocatalyst must be taken into account in gas-phase photocatalytic degradation.

In humid condition, the surface of TiO2 was covered by a water layer, but the surface of SiC keeps uncovered (as shown in the left part of the following picture). Due to the special staggered type energy band structure heterojunction, the photogenerated electrons gathered on TiO2 and holes enriched on SiC. Both of which participated in the degradation of toluene in different ways (as shown in the right part of the following picture).Figure optionsDownload as PowerPoint slideHighlights
► To fully photocatalytic oxidize toluene in high concentration is a great challenge.
► Hydrophobic SiC is coupled with hydrophilic TiO2 to enhance the mineralization.
► The separation of the photogenerated electron−hole pairs was promoted.
► Electrons and holes participate in the degradation independently.
► Toluene is decomposed and fully mineralized.