Synthesis,\nCharacterization, and Photocatalytic Properties\nof SnO₂/Rutile TiO₂/Anatase TiO₂ Heterojunctions\nModified by Pt

Abstract

To improve the separation\nrate of photogenerated electrons and\nholes, a SnO₂/rutile TiO₂ (R-TiO₂)/anatase TiO₂ (A-TiO₂) photocatalyst modified\nby Pt nanoparticles with three pairs of heterojunctions was fabricated\nby a facile hydrothermal method. Transmission electron microscopy\n(TEM) and high-resolution transmission electron microscopy (HRTEM)\nclearly illustrated the structure of the three pairs of heterojunctions\nconnected to each other. Heteronanostructure photocatalysts with increased\nspecific surface area could offer more active sites when contacting\npollutants, resulting in improved photocatalytic activity. The red\nshift in UV–vis diffuse reflectance spectra (DRS) indicated\nthe utilization of visible-light. Photoluminescence (PL) and photoelectrochemical\n(PEC) measurements suggested the enhancement of electron and hole\nseparation, in accordance with the results obtained for the photocatalytic\noxidation of decomposing toluene over 4 h. A catalyst containing 1\nwt % Pt/10 at. % SnO₂/R-TiO₂/A-TiO₂ exhibited the best photocatalytic mineralization rates of toluene:\n40.9% and 72.3% under visible-light and UV-light irradiation, respectively.\nA proposed mechanism was elaborated to reveal the effective photocatalytic\nprogress of charge transfer along multiple pathways along the three\npairs of heterojunctions doped with Pt.