Gold nanoparticle-modified TiO2/SBA-15 nanocomposites as active plasmonic photocatalysts for the selective oxidation of aromatic alcohols

Abstract

The catalytic performance of noble-metal on mesoporous silica hosts has been widely investigated because the effects of surface plasmon resonance can open new avenues for the improvement of catalytic performance under light irradiation. In this study, a series of photoactive Au/TiO₂/SBA-15 catalysts were developed for the selective oxidation of alcohols to corresponding aldehydes and ketones. The catalysts thus developed were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), scanning transmission electron microscopy energy-dispersive spectrometry, X-ray photoelectron spectroscopy (XPS), transient photocurrent response and electrochemical impedance spectroscopy (EIS). Au and small TiO₂ nanoparticles (NPs) were uniformly anchored into the SBA-15 channels by the microwave-assisted alcohol reduction, resulting in the increase of the interfacial area between gold and titania; this increase in turn results in better catalytic performance of the Au₂/TiO₂/SBA-15 catalysts toward the selective oxidation of aromatic alcohols to aromatic aldehydes (ketones) as a result of the efficient pore confinement and visible-light absorption by the LSPR effect. A scheme with respect to the enhancement of photooxidation induced by the LSPR effect on the Au NP-decorated TiO₂/SBA-15 composite was proposed.