Nano Pt-TiO_2 for an efficient one-pot photocatalytic synthesis of quinaldines from anilines and ethanol

摘要

Nanosized platinum particles loaded on the TiO_2 nanoparticles were prepared to assess its photocatalytic activity in simple one-pot synthesis of quinaldines from anilines in ethanol using UV light. The catalyst was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy, X-ray photoelectron spectra (XPS), Brunauer-Emmer-Teller surface area, atomic force microscope and diffuse reflectance spectra. XRD patterns revealed that the crystal structure of Pt-TiO_2 resembled anatase phase of TiO_2. The UV-Vis spectra indicated an increase in absorption of visible light when compared to TiO_2. XPS analysis reveals that platinum particles are present mainly in metallic form. Furthermore, TEM analysis showed non-spherical-shaped Pt-TiO_2 nanoparticles of the diameter 10-30 nm. Upon irradiation in the presence of Pt-TiO_2, aniline and oxidation products derived from ethanol undergo condensation-cyclization to afford quinaldines. Higher efficiency of Pt-TiO_2 than Au-TiO_2 in the conversion of aniline to quinaldines is due to the higher work function of Pt.