Electrodeposition of Multilayered Bimetallic Nanoclusters of Ruthenium and Platinum via Surface-Limited Redox−Replacement Reactions for Electrocatalytic Applications

Abstract

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.

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

“…In 2009, Cukrowski's group reported for the first-time the fabrication of electrodeposited multilayer Ru-Pt clusters on glassy carbon for ORR in alkaline solution [72]. Yancey et al electrochemically synthesized Au@Pt dendrimer-encapsulated nanoparticles and discovered that Au 147 @Pt DENs (dendrimer encapsulated nanoparticles) exhibited higher ORR activity than Au and Pt nanoparticles alone [89].…”

Recent Advances in the Growth of Metals, Alloys, and Multilayers by Surface Limited Redox Replacement (SLRR) Based Approaches

“…An alternative way to very closely translate the SLRR concept to a practical language is the flow-cell approach allowing for successive flux of different electrolytes through the deposition cell. This approach was introduced first in early nineties of last century by Stickney et al for the growth of compound semiconductors be electrochemical atomic layer deposition [29] and adopted more recently by Cukrowski et al for studies relevant to SLRR deposition [47]. In another recently introduced approach, a simplification of the shuttling approach proposed by Dimitrov et al resulted in the establishment of the so called one-cell approach that brought both metal (sacrificial and growing) ions in a single electrochemical cell [31].…”

“…Typically, thin Au films deposited on glass slides are used as WE. The SLRR cycles are controlled by the custom software that serves to open and close valves based on prescribed duration and/or potential thresholds with a main objective to run successively electrolytes with specific functionality and rinsing water as needed for multi-cycle SLRR deposition [47]. Some sophistications of the flow-cell approach proposed recently by Cukrowski et al led to the development of a setup with exchangeable cells with controlled hydrodynamic flux profile that enable controlled electrolyte hydrodynamics capability [54].…”

Physico–chemical Modelling of Adlayer Phase Formation via Surface–limited Reactions of Copper in Relation to Sequential Electrodeposition of Multilayered Platinum on Crystalline Gold

“…A custom-built automated instrumental setup described previously [9] was used for all electrochemical deposition experiments. The setup consisted of piston pumps with electrolyte reservoirs in digitally-controlled exchange units (765 Dosimat, Metrohm), the PGSTAT30 electrochemical workstation operated in potentiostatic mode and a three-electrode flow-cell ( Figure 1A) utilising a Ag/AgCl/3M KCl reference electrode (model 6.0727.000, Metrohm Autolab); unless otherwise stated, potentials are reported versus this reference electrode.…”

“…Electrochemical deposition of transition metals, with atomic control using single-step or multistep surface-limited redox-replacement (SLRR) reactions, is of fundamental and potential technological importance in fabrication of monolayer-decorated nanoparticles, monolayercoated surfaces, epitaxial ultra-thin films, as well as multilayered nanoclusters [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In a typical SLRR reaction (Reaction (1)), an adlayer of a metal M formed electrochemically through underpotential deposition (UPD) [15,16] …”