(729a) CO Chemisorption IR Studies On Supported Nanofabricated Pt/TiO2 Catalytic Junctions

Pt/TiO2 model catalysts consisting of a large array of parallel Pt nanowires on TiO2/Au substrates (grown on silicon wafers) have been prepared. The nanowires are fabricated using electron beam lithography followed by Pt metal deposition and a liftoff process. The different samples have Pt nanowires of different widths varying from 25 nm to 90 nm with a separation of 200 nm. CO adsorption desorption studies have been performed on these low area nanofabricated catalysts using ENIRAS technique developed in our lab which causes a large signal enhancement due to optical interference between different layers of the Pt/TiO2/Au layered structure. The results are compared with similar studies on Pt thin films deposited on TiO2 and SiO2 supports. The results show a gradual shift in the CO stretching mode peak position with a change in the width of the nanowires. This shift could be related to the boundary sites near metal support junctions and appears to change linearly with length of Pt/TiO2 interface per unit Pt area of the catalysts. Further investigations involving imposing external electric fields on Pt sites near the metal support boundary by applying an external voltage to the Pt/TiO2 junction is presently underway. The aim of this work is to investigate the boundary sites which can play an important role in the supported catalysts.