Photocatalytic Degradation of Acetone over a V2O5/LaF3 Catalyst under Visible Light

Visible light active photodegradation catalysts were prepared by doping V 2 O 5 into a LaF 3 matrix. In the photodegradation of acetone, the highest conversion was obtained over a catalyst containing 16.0 atom % vanadium. When VO x /LaF 3 catalysts were calcined below 673 K, a LaF 3 phase was observed in XRD characterization. At even higher catalyst calcination temperatures (higher than 673 K), LaF 3 and LaVO 4 phases were observed in VO x /LaF 3 catalysts. The laser Raman and FTIR characterizations indicated that there are V 2 O 5 species (possibly amorphous) and LaVO 4 phases formed in the VO x /LaF 3 catalysts. The photoluminescence characterization showed that the photoelectron-hole pair recombination rate over the VO x /LaF 3 catalyst was slower than that over pure V 2 O 5 . The UV-vis spectrum of VO x /LaF 3 indicates that this material is sensitive under visible light with wavelengths of <600 nm. The V 2 O 5 species in the LaF 3 matrix might be the active sites, but the LaVO 4 phase is not active in the photodegradation reaction of acetone. Almost all V 2 O 5 was converted to the LaVO 4 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 LaF 3 matrix acted in isolating the V 2 O 5 species and retarding the electron-hole pair recombination. Hence, the doping of V 2 O 5 into the LaF 3 matrix reduced the recombination rate of electron-hole pairs and enabled VO x /LaF 3 to have a high activity under visible light for the photodegradation of acetone.