Abstract:
Electrochemical, surface and bulk compositional properties of multilayered nanoclusters of Pt and Au, electrochemically deposited
on 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 electrocatalytic
applications. Variations in open–circuit potentials during redox–replacement steps indicated thermodynamically–favored formation
of Pt(s) and Au(s). Unique bimetallic interfacial active sites, Pt|Au or Au|Pt, were effectively generated as evidenced by their
distinct surface electrochemistry and multicomponent X–ray photoelectron spectral features. The bulk and surface–to–near surface
distribution of Pt and Au appeared to be influenced by the stoichiometry of the surface redox–replacement reactions and sequential
dealloying processes through which the nanoclusters were synthesized. Interactions between metal centers, carbon and oxygen
containing surface functional groups on the glassy carbon appeared to have played a significant role in the overall stabilization
and catalytic activity of the nanoclusters. Profound effects were also found on interfacial charge–transfer and adsorptive properties
involving carbon monoxide and its subsequent electrooxidation to CO2, as well as on the electrocatalytic activity involving formic
acid oxidation reaction, where the Pt–rich (Pt|Au) exhibited the highest activity.
