Synthesis of Mesoporous Pd-Doped TiO2 Templated by a Magnetic Recyclable Ionic Liquid for Efficient Photocatalytic Air Treatment

Mesoporous palladium-doped TiO2 with anatase phase and high surface area was successfully synthesized by using a green sol–gel method with an ionic liquid (IL; 1-butyl-3-methylimidazolium ferric chloride), as a template. This IL could be recovered and reused by magnetic separation after synthesis. The synthesized mesoporous sample was characterized through FESEM, XPS, XRD, and N2 adsorption–desorption methods. The photocatalytic activity of Pd-doped titania in ionic liquid (Pd/IL-TiO2) for the degradation of NOx and CO was investigated. The results demonstrated that the ionic liquid ([BMIM]FeCl4), in combination with Pd dopant, retarded the creation of nanocrystals, with a small grain size (9.1 nm) and, presumably, a larger surface area. With regard to the bare IL-TiO2 sample, the optical band gap calculated for the Pd/IL-TiO2 obtained was 2.68 eV in comparison to 2.77 eV. Pd/IL-TiO2 presented much better NOx (88%) and CO (74%) photodegradation as compared to undoped IL-TiO2 (59 and 56%) in the same resid...