Synthesis of Highly Dispersed Platinum Nanoparticles on Ti-Containing Mesoporous Silica Using Photo-Assisted Deposition

A simple and unique route to synthesize the nano-size Pt particles using mesoporous silica support including single-site Ti-oxide moiety (Ti-HMS) under UV-light irradiation has been developed. By the photo-assisted deposition (PAD) method, a Pt precursor can be deposited from aqueous solution of H2PtCl6 directly on the photo-excited isolated Ti-oxide moiety. The subsequent reduction with H-2 generates the nano-sized Pt metal particles (PAD-Pt/Ti-HMS). The deposition of Pt precursor onto the Ti-HMS can be recognized by the observation of the decrease in the intensity of the preedge in the Ti K-edge XANES spectrum, demonstrating that the Pt precursor underwent anchoring on the single framework Ti4+ center of Ti-HMS under UV-light irradiation. The lower intensity of the Pt-Pt bono of the PAD-Pt/Ti-HMS than that of Pt foil in the Fourier transforms of Pt L-III-edge EXAFS spectra clearly suggests the formation of the Pt nanoparticles. The PAD-Pt/Ti-HMS exhibited the higher catalytic activity for the hydrogenation of nitrobenzene to aniline and the NO reduction than the catalyst prepared by the conventional impregnation.