Photocatalytic degradation of acetone over a V2O5/LaF3 catalyst under visible light

Visible light active photodegradation catalysts were prepared by doping V2O5 into a LaF3 matrix. In the photodegradation of acetone, the highest conversion was obtained over a catalyst containing 16.0 atom % vanadium. When VQ,/LaF3 catalysts were calcined below 673 K, a LaF3 phase was observed in XRD characterization. At even higher catalyst calcination temperatures (higher than 673 K), LaF3 and LaVO4 phases were observed in VOx/LaF3 catalysts. The laser Raman and FTIR characterizations indicated that there are V2O5 species (possibly amorphous) and LaVO4 phases formed in the VOx/LaF3 catalysts. The photoluminescence characterization showed that the photoelectron-hole pair recombination rate over the VOx/LaF3 catalyst was slower than that over pure V2O5. The UV-vis spectrum of VOx/LaF3 indicates that this material is sensitive under visible light with wavelengths of < 600 nm. The V2O5 species in the LaF3 matrix might be the active sites, but the LaVO4 phase is not active in the photodegradation reaction of acetone. Almost all V2O5 was converted to the LaVO4 phase when catalysts were calcined at temperatures higher than 723 K, and the catalysts calcined at high temperatures lost activity during acetone degradation. The investigation shows that the LaF3 matrix acted in isolating the V2O5 species and retarding the electron-hole pair recombination. Hence, the doping of V2O5 into the LaF3 matrix reduced the recombination rate of electron-hole pairs and enabled VOx/LaF3 to have a high activity under visible light for the photodegradation of acetone.