Pinning platinum and Pt-oxide nanoparticles on graphite

Nanoparticles of platinum oxide are deposited onto a highly oriented pyrolitic graphite (HOPG) substrate. The platinum oxide particles are formed by flowing oxygen gas through a hot (1425 K) platinum capillary tube in vacuum. By controlling the temperature and the gas flow, a condition can be reached so that Pt atoms are evaporated from the inner walls of the tube and subsequently oxidised by oxygen either before or after landing on HOPG. Atomic oxygen, produced inside the tube through thermal cracking of O2, is co-deposited onto HOPG. Atomic oxygen form strong bonds with carbon atoms on the HOPG surface and hence a significant number of pinning sites are created for the incoming platinum and platinum oxide particles.