Single-step synthesis of a highly active photocatalyst for oxidation of trichloroethylene

We have developed a single-step synthesis approach to fabricate ZnO/TiO2-SiO2 monoliths as active photocatalysts. The photocatalysts were thoroughly characterized by XRD, FTIR, SEM, TEM, EDX and XPS. The synthetic manipulation shows evidence of the feasibility to load high amounts of the ZnO into the support matrixes (i.e. up to 25%). The developed ZnO/TiO2-SiO2 materials were used as effective photocatalysts to oxidize trichloroethylene (TCE) to HCl and CO2 in the presence of UV light at lambda = 365 nm. The TEM profiles and EDX findings indicated that ZnO particles were homogeneously dispersed into TiO2-SiO2 matrixes. On such heterogeneous photocatalytic systems, the oxidation affinity of TCE was substantially affected by the loading amount of ZnO particles onto the TiO2-SiO2 matrixes, indicating the exclusive effect of the ZnO nanoparticles on TCE photocatalytic oxidation. Our results showed that the photoactivity of ZnO/TiO2-SiO2 monoliths was decreased from 96% to 80% after 5 reuse cycles. The formation of ZnO inside TiO2-SiO2 led to strengthen the frameworks of TiO2-SiO2 matrixes. The ZnO/TiO2-SiO2 monoliths thus achieve high performance and are therefore highly applicable to environmental cleanup of toxic Compounds. (c) 2008 Elsevier B.V. All rights reserved.