Ruthenium–platinum bimetallic catalysts with controlled surface compositions and enhanced performance for methanol oxidation

Synthesis of Highly Active Pd@Cu–Pt/C Methanol Oxidation Electrocatalysts via Continuous, Co-Electroless Deposition

“…This bifunctional mechanism is believed to be responsible for the enhanced activity of the Ru–Pt system for methanol electrooxidation [ 11 ]. Indeed, the addition of ruthenium to platinum supported on carbon using electroless deposition methods has been shown [ 12 , 13 ] to be an effective method of dramatically increasing DMFC activity, corroborating the bifunctional mechanism proposed earlier by Watanabe [ 10 , 11 , 12 ], among others.…”

“…Each voltammogram shows two remarkable anodic peaks, one in the forward scan (I f ) and the other in the backward scan (I b ). The forward current, I f at ~0.85 V, normalized to the mass of Pt (mass activity), was measured as the marker for MeOH electrooxidation activity, in accordance with prior literature [ 11 , 12 ]. Figure 6 a,b shows two CV traces for two samples, Cu 0.23 Pt 1 and Cu 1.6 Pt 1 , respectively.…”

“…Cyclic voltammetry (CV) procedures are largely repeated from previous work with a different catalyst system studying the same reaction [ 12 ]. Cyclic voltammetry studies were performed using a 5 mm diameter Pt disk coated with catalyst as the working electrode with a bare Pt wire used as the counter electrode.…”

“…It has been experimentally shown that the d-band of Pt can be altered by either lattice compression or expansion, which changes the adsorption strength of CO on Pt [ 8 , 9 ]. Bifunctionality involves the addition of a second metal in close proximity to Pt that functions as an adsorption site for the decomposition of H 2 O to give OH ads, which can react with Pt-CO to form CO 2 by reaction (3) [ 5 , 10 , 11 , 12 ]. This bifunctional mechanism is believed to be responsible for the enhanced activity of the Ru–Pt system for methanol electrooxidation [ 11 ].…”

“…This process ensures that the secondary metal is deposited only on the primary metal and not on the support [ 15 ]. For example, in earlier work [ 12 ], bimetallic catalysts with different monolayer (ML) coverages of Ru on 20 wt % Pt/C were prepared by ED and evaluated for methanol electrooxidation. The Pt mass activity (425A/g Pt ) of the sample with 0.5 ML Ru coverage (1.1 wt % Ru—surface Pt:Ru = 1:1) was seven times higher than a 20 wt % Pt/C catalyst and 3.5 times higher than a commercial catalyst with a 1:1 Pt: Ru bulk atomic ratio of 6.8 wt % Ru—13.2 wt % Pt/C.…”