Photocatalytic toluene degradation over Bi-decorated TiO2: Promoted O2 supply to catalyst’s surface by metallic Bi

In the photocatalytic volatile organic compounds (VOCs) degradation, the accumulation of intermediate products on the surface of catalysts could cause a decrease in activity through retarding reactant (e.g. O 2 ) supply to surface active sites. Herein, Bi decorated TiO 2 photocatalysts (Bi/TiO 2 ) for photocatalytic toluene degradation were prepared and systematically studied. It is found that metallic Bi modification improves the ability of photocatalysts to capture O 2 . As a result, the activities of the Bi/TiO 2 photocatalysts are obviously higher than that of the TiO 2 for photocatalytic toluene degradation, and the productions of photogenerated reactive oxygen species ( O 2 − and H 2 O 2 ) over the Bi/TiO 2 photocatalysts are almost equal to that over the TiO 2 despite the fact that the separation efficiency of photoinduced charge carriers is decreased after the addition of Bi. Adsorbed benzaldehyde is the main surface intermediate on the surface of the Bi/TiO 2 photocatalysts, whereas plenty of more readily oxidized aliphatic carboxylate species was monitored on the surface of the TiO 2 , which can be attributed to insufficient O 2 supply to the TiO 2 surface. This further indicates the positive role of the promoted O 2 supply by Bi in the photocatalytic toluene degradation. The present work offers a new window for addressing the catalyst deactivation in the photocatalytic VOCs degradation.