Electrocatalytic properties of platinum anchored to the surface of highly oriented pyrolytic graphite

Nano-sized particles of platinum deposited on highly oriented pyrolytic graphite (HOPG) electrolessly (average sized = 3.4 nm) or electrochemically (d = 20 nm) and polycrystalline platinum are compared. The dispersed electrodes exhibit special features in the oxidation of ethylene glycol and adsorbed carbon monoxide. In particular, they reduce the overpotential of these processes. Possible reasons for the observed distinctions are discussed. The potential cycling leads to coalescence of nano-sized Pt particles on HOPG. As a result, their size distribution expands, and the distribution maximum shifts towards large sizes (d = 6.4 nm). This seriously complicates use of Pt/HOPG as a model electrode for investigating the size effect.