Effect of the Co-deposition of Pd and Pt on TiO 2 Photoactivity

Abstract

TiO2 was obtained by a simple sol–gel synthesis and subsequently modified by the addition of Pt and/or Pd particles on the surface by photodeposition. These photocatalysts were characterised by X-ray diffraction analysis, UV–Vis diffuse reflectance spectra, Brunauer–Emmett–Teller measurements, Fourier transform infrared spectroscopy, transmission electron microscopy, electron dispersive spectroscopy and X-ray photoelectron spectroscopy. Their photocatalytic activity was studied by following the degradation, mineralisation and detoxification of solutions of phenol, propanil and methylene blue. For comparison purposes, different commercial TiO2 catalysts were also tested: Kronos vlp7000, Millenium PC100, Aeroxide P90 and Aeroxide P25. This latter catalyst was also modified with Pt and/or Pd. The degradation kinetics of all the pollutants in aqueous solutions satisfactorily followed the pseudo-first order according to the Langmuir–Hinshelwood model in conditions of low concentration values. It was found that the simultaneous photodeposition of Pt and Pd contributed to enhancing photoactivity more than the individual deposition of either Pt or Pd.