Significant Reduction in Adsorption Energy of CO on Platinum Clusters on Graphite

We have studied desorption of CO on a Pt-deposited highly oriented pyrolytic graphite (HOPG) surface by temperature programmed desorption of CO (CO-TPD), scanning tunneling microscope (STM), and He atoms scattering (HAS). A desorption peak of CO at a significantly lower temperature of similar to 270 K with a heating rate of 0.5 K/s is observed for Pt clusters on a flat terrace of HOPG. STM results indicate that the height of Pt clusters on the terraces of the HOPG surface is monatomic. It is concluded that the significant reduction in CO adsorption energy is due to a modified electronic structure as a result of the interface interaction between Pt clusters and the HOPG surface.