Nanoscale platinum(0) clusters in glassy carbon: synthesis, characterization, and uncommon catalytic activity

Abstract

The preparation of nanoscale metal clusters is important because of their potential for high catalytic activity. Successful methods for the preparation of metal clusters include metal ion reduction to give small crystallites on various surfaces or colloidal dispersions, metal ion reduction into polymer films coated on electrode surfaces, decomposition of organometallic compounds, evaporation of metals, and sol-gel processes. We expected that the incorporation of metals on the molecular level in a carbon precursor, followed by thermolysis, would result in a conductive, dimensionally stable carbon matrix containing metal particles of controlled composition, size, and catalytic activity. We report here the synthesis of nanoscale platinum(0) clusters in their catalytic activity with respect to H{sup +} and dioxygen reduction. Platinum was incorporated into a glassy carbon precursor by the reaction of poly(phenylenediacetylene) with (ethylene)bis(triphenylphosphine)platinum(O). The coordination of the platinum complex to the triple bond of the oligomer was carried out in approximately 1:4 and 1:2 ratios. The resulting oligomers were heated to 600 degrees Celsius to give platinum-doped glassy carbon as pellets or thin films on conventional glassy carbon. Electrocatalytic activity of the thin films were evaluated and found to have similar current densities to those of electroformed platinum microparticles. However, the filmsmore » can be prepared with up to two orders of magnitude lower platinum loadings without sacrificing catalytic activity.« less