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

Abstract

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 H2-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/TiO2MSD-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.