Multilayered nanoclusters of platinum and gold : insights on electrodeposition pathways, electrocatalysis, surface and bulk compositional properties

摘要

Electrochemical, surface and bulk compositional properties of multilayered nanoclusters of Pt and Au, electrochemically depositedon glassy carbon under conditions involving sequential surface–limited redox–replacement reactions (performed at open–circuit)and voltammetric dealloying of templating adlayers of electrodeposited Cu, have been studied in the direction of electrocatalyticapplications. Variations in open–circuit potentials during redox–replacement steps indicated thermodynamically–favored formationof Pt(s) and Au(s). Unique bimetallic interfacial active sites, Pt|Au or Au|Pt, were effectively generated as evidenced by theirdistinct surface electrochemistry and multicomponent X–ray photoelectron spectral features. The bulk and surface–to–near surfacedistribution of Pt and Au appeared to be influenced by the stoichiometry of the surface redox–replacement reactions and sequentialdealloying processes through which the nanoclusters were synthesized. Interactions between metal centers, carbon and oxygencontaining surface functional groups on the glassy carbon appeared to have played a significant role in the overall stabilizationand catalytic activity of the nanoclusters. Profound effects were also found on interfacial charge–transfer and adsorptive propertiesinvolving carbon monoxide and its subsequent electrooxidation to CO2, as well as on the electrocatalytic activity involving formicacid oxidation reaction, where the Pt–rich (Pt|Au) exhibited the highest activity.