Thin film nano-photocatalysts with low band gap energy for gas phase degradation of p-xylene: TiO2 doped Cr, UiO66-NH2 and LaBO3 (B = Fe, Mn, and Co).

By dip-coating technique the thin films of nano-photocatalysts TiO 2 , Cr-doped TiO 2 , LaBO 3 perovkites (B = Fe, Mn, and Co) prepared by sol-gel method, and UiO66-NH 2 prepared by a solvothermal were obtained and employed for gas phase degradation of p-xylene. Physicochemical characteristics of the catalysts were examined by the methods of BET, SEM, TEM, XRD, FT-IR, and UV-Vis spectroscopies. The thickness of film was determined by a Veeco-American Dektek 6M instrument. The activity of catalysts was evaluated in deep photooxidation of p-xylene in a microflow reactor at room temperature with the radiation sources of a UV (λ = 365 nm) and LED lamps (λ = 400–510 nm). The obtained results showed that TiO 2 and TiO 2 doped Cr thin films was featured by an anatase phase with nanoparticles of 10-100 nm. Doping TiO 2 with 0.1 %mol Cr 2 O 3 led to reduce band gap energy from 3.01 down to 1.99 eV and extend the spectrum of photon absorption to the visible region (l = 622 nm). LaBO 3 perovkite thin films were also featured by a crystal phase with average particle nanosize of 8-40 nm, a BET surface area of 17.6 - 32.7 m 2 /g and band gap energy of 1.87- 2.20 eV. UiO66-NH 2 was prepared in the ball shape of 100 – 200 nm,  a BET surface area of 576 m 2 /g and a band gap energy of 2.83 eV. The low band gap nano-photocatalysts based on Cr-doped TiO 2 and LaBO 3 perovkites exhibited highly stable and active for photo-degradation of p-xylene in the gas phase under radiation of UV-Vis light. Perovkite LaFeO 3 and Cr-TiO 2 thin film were the best photocatalysts with a decomposition yield being reached up to 1.70 g p-xylene /g cat .