Platinum-carbon electrocatalytic composites via liposome-directed electrodeposition at conductive diamond

A Pt precursor was entrapped in phosphatidylcholine-cholesterol vesicles and the liposomal suspension was used for direct electrodeposition of a Pt-based catalyst on boron-doped diamond (BDD). The average size of the deposited particles (ca. 15 to ca. 40 nm) is closely related to that of the liposomes and Pt particles are partially embedded into a carbonaceous matrix. Methanol anodic oxidation was used for gauging the electrocatalytic activity of the composites and it was found that the electrodeposition with prior adsorption of the liposomes enables more efficient use of platinum. Without preliminary adsorption, a much higher resistance to fouling was observed for the electrocatalyst. This behavior was ascribed to the presence on the electrodes surface of PtO2 and of a higher amount of oxygenated carbon states. These species act as oxygen donors contributing to an easier eviction of the adsorbed CO, thus partially regenerating active sites from the electrocatalyst surface.