Electro-oxidation mechanisms of methanol and formic acid on Pt-Ru alloy surfaces

• Published in: Electrochimica acta Vol. 40; no. 1; pp. 91 - 98
• Main Authors: Marković, Nenad M., Gasteiger, Hubert A., Ross, Philip N., Jiang, Xudong, Villegas, Ignacio, Weaver, Michael J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 1995; Elsevier
• Subjects: Chemistry; electrocatalysis; Electrochemistry; Exact sciences and technology; formic acid; FTIR; General and physical chemistry; Kinetics and mechanism of reactions; methanol; Pt-Ru alloys; formic acid; Pt-Ru alloys; methanol; electrocatalysis; FTIR; Fourier transformation; Ruthenium; Transition metal; Experimental study; Acidic solution; Sulfuric acid; Infrared spectrometry; Electrocatalysis; Transition metal Alloys; Adsorption; Ruthenium Alloys; Platinum; Formic acid; Reaction mechanism; Oxidation; Carbon monoxide; Platinum Alloys; Electrochemical reaction; Methanol
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/0013-4686(94)00241-R

Voltammetry combined with single-potential alteration infrared spectroscopy (SPAIRS) were used to study the extent of adsorbed CO produced at Pt, Ru and Pt-Ru alloy electrodes during methanol and formic acid oxidation in acidic supporting electrolyte. The addition of even small atomic fractions of Ru to Pt surfaces caused a decrease in the quasi-steady-state level of CO on the surface for both reactions. This result is consistent with the bifunctional mechanism proposed previously: Ru sites nucleate oxygen containing species at ≈0.2-0.3 V lower potential than on the pure Pt surface; the adsorption of methanol occurs on Pt ensembles producing adsorbed CO; in the case of formic acid, adsorption is equally facile at Pt-Pt, Pt-Ru and Ru-Ru sites, with dehydration producing adsorbed CO; the further electro-oxidation of CO is catalyzed by oxygen-containing species nucleated onto nearby by Ru atoms. The improved efficiency of the alloy surfaces for oxidation of adsorbed CO at low potential shifts the rate limiting step to the adsorption step, which results in very low coverages of the surfaces by adsorbed CO.