Abstract
Noble metals (Au, Pd and Pt) have been photodeposited onto hexagonal mesoporous RuO2-TiO2 nanocomposites to study their influence on the photocatalytic activity under UV and visible lights by determination of the formation rate of HCHO generated by photooxidation of CH3OH in aqueous solution. X-ray diffraction (XRD) patterns and N-2 sorption isotherms reveal that highly crystalline TiO2 and mesoporous structure have been formed with high surface area (150-180 m(2)/g) and pore diameter ranging from 6.8 to 7.3 nm. TEM measurements show that the framework of the highly crystalline mesoporous RuO2-TiO2 is composed of anatase phase grown along [1 0 1] direction. The dependence of HCHO formation rate on the noble metals/RuO2-TiO2 nanocomposites, behaves quite differently depending on noble metals as electrons sink. Under UV light, the findings reveal that Pd/RuO2-TiO2 offers an improvement in term photooxidation rate of CH3OH and photonic efficiencies over Pt/RuO2-TiO2 and Au/RuO2-TiO2. However, under visible light, the photocatalytic activity of mesoporous RuO2-TiO2 containing Au nanoparticles towards CH3OH oxidation is remarkable and the photonic efficiency of RuO2-TiO2 has been improved two times. Pt and Pd nanoparticles could not be observed in any improvement in photocatalytic activity of RuO2-TiO2 under visible light. (c) 2012 Elsevier B.V. All rights reserved.