Deposition of Pt nanoparticles on TiO2 by pulsed direct current magnetron sputtering for selective hydrogenation of vanillin to vanillyl alcohol

Pulsed direct current magnetron sputtering (PDC-MSD) was employed for the deposition of Pt nanoparticles (ca. 0.1 wt.%) on anatase TiO2 powder. According to the H-2-TPR, XPS, and TEM-EDX results, the characteristics and properties of the deposited nanoparticles depended on the deposition time. During the initial deposition stage (45-90 sec), low-coordinated small spherical Pt nanoparticles were formed. Prolonging the deposition time (135-180 sec), led to the formation of larger Pt nanoparticles, which strongly interacted with the TiO2. The catalytic activities of the prepared Pt/TiO2 with different deposition times in the aqueous phase partial hydrogenation of vanillin to vanillyl alcohol ranged as follows: Pt/TiO2 MSD-45 < Pt/TiO2MSD-90 < Pt/TiO 2MSD-180 < Pt/TiO2 MSD-135, which was in good agreement with the atomic Pt/Ti ratio and coordinated surface Pt atoms on the catalyst surface. The high catalytic activity of Pt/TiO2 MSD-135 was attributed to the presence of well-dispersed small Pt nanoparticles with more highly-coordinated Pt surface atoms deposited on the TiO2 anatase. PDC-MSD has been proven to be a more effective method for the preparation of supported metal catalysts, compared to those obtained by conventional impregnation technique.