An electrochemical synthesis of multilayered bimetallic Ru|Pt nanoclusters, supported on glassy carbon, is reported for the first time. The novel nanoclusters were synthesized via surface-limited redox-replacement reactions involving sacrificial Cu, deposited prior to the formation of each individual noble metal layer, in a sequential fashion. It has been shown that the Cu adlayers control the morphology and electrochemical properties of the resultant nanostructures. Sequentially deposited Ru|Pt nanoclusters exhibited superior electrocatalytic activity (when compared to equivalent monometallic Pt and an alloy-type codeposited Pt-Ru nanostructures) with respect to methanol electrooxidation in an acidic medium. Moreover, it has been established that the electrochemical process taking place at the Ru|Pt nanoclusters followed the bifunctional mechanism. Electrokinetic studies of the oxygen reduction reaction (ORR) were also performed. Analysis of hydrodynamic linear sweep voltammetric experiments, performed at various flow rates on oxygen-saturated acidic medium, revealed that the Pt and Ru|Pt nanoclusters exhibited direct four- and two-electron ORR pathways, respectively. A specially designed electrochemical flow-cell was used for automated sequential electrodeposition of the multilayered nanoclusters of predefined composition and electrochemical and electrocatalytic investigations.

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Electrochemical physico-chemical models, describing isothermically surface coverage dependency with electrode potential of underpotentially deposited Cu adlayers (Cu UPD ) as well as successive surface-limited redox replacement (SLRR) reactions between Cu UPD and PtCl 6 2-, to form multilayered Pt deposits on crystalline Au, have been explored. Modelling of such phase formation phenomena take into account heterogeneity effects and extent of adatom interactions within the adlayers on the base Au substrate and gradually formed Pt multilayered deposits.

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 CO 2 , as well as on the electrocatalytic activity involving formic acid oxidation reaction, where the Pt-rich (Pt|Au) exhibited the highest activity.3