Mesostructured Pt/TiO2 Nanocomposites as Highly Active Photocatalysts for the Photooxidation of Dichloroacetic Acid

Mesoporous Pt/TiO2 nanocomposites have been synthesized by using two pathways: (1) the in-situ preparation of Pt/TiO2 nanocomposites was carried out using a one-step synthesis by dissolving the Pt and TiO2 precursors in the presence of a triblock copolymer as the structure-directing agent followed by drying, calcinations, and reduction under H2 gas. (2) Platinum particles have been photochemically deposited onto mesoporous TiO2. The TEM images of the mesoporous Pt/TiO2 nanocomposites calcined at 450 °C demonstrate that the TiO2 nanoparticles with an average diameter of about 10 nm are not agglomerated and are quite uniform in size and shape. Following the photodeposition process, the Pt nanoparticles are well-dispersed and highly uniform, exhibiting diameters of ∼3 nm; however, following the in situ preparation, the Pt particles are reaching diameters of approximately 15 nm, most likely as a result of the calcination and reduction at high temperatures. The photocatalytic activity of the newly synthesized ...