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

Nenad M. Marković; Hubert A. Gasteiger; Philip N. Ross; Xudong Jiang; Ignacio Villegas; Michael J. Weaver

doi:10.1016/0013-4686(94)00241-R

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

Nenad M. Marković, Hubert A. Gasteiger, Philip N. Ross, Xudong Jiang, Ignacio Villegas, Michael J. Weaver

Research output: Contribution to journal › Article › peer-review

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Abstract

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.

Original language	English
Pages (from-to)	91-98
Number of pages	8
Journal	Electrochimica Acta
Volume	40
Issue number	1
DOIs	https://doi.org/10.1016/0013-4686(94)00241-R
State	Published - Jan 1995
Externally published	Yes

Keywords

FTIR
Pt-Ru alloys
electrocatalysis
formic acid
methanol

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10.1016/0013-4686(94)00241-R

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@article{68a43f11a27844578a4a86d37094f62f,

title = "Electro-oxidation mechanisms of methanol and formic acid on Pt-Ru alloy surfaces",

abstract = "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.",

keywords = "FTIR, Pt-Ru alloys, electrocatalysis, formic acid, methanol",

author = "Markovi{\'c}, {Nenad M.} and Gasteiger, {Hubert A.} and Ross, {Philip N.} and Xudong Jiang and Ignacio Villegas and Weaver, {Michael J.}",

note = "Funding Information: Acknowledgements-We would like to thank Lee Johnson for the machining and polishing of the alloy samples. This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, ORice of Transportation Technologies, Electric & Hybrid Propulsion Division of the U.S. Department of Energy under Contract No. DE-AC03-76SFOOO98( to P. N. Ross), as well as by the U.S. Office of Naval Research and the National Science Foundation (to M. J. Weaver).",

year = "1995",

month = jan,

doi = "10.1016/0013-4686(94)00241-R",

language = "English",

volume = "40",

pages = "91--98",

journal = "Electrochimica Acta",

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TY - JOUR

T1 - Electro-oxidation mechanisms of methanol and formic acid on Pt-Ru alloy surfaces

AU - Marković, Nenad M.

AU - Gasteiger, Hubert A.

AU - Ross, Philip N.

AU - Jiang, Xudong

AU - Villegas, Ignacio

AU - Weaver, Michael J.

N1 - Funding Information: Acknowledgements-We would like to thank Lee Johnson for the machining and polishing of the alloy samples. This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, ORice of Transportation Technologies, Electric & Hybrid Propulsion Division of the U.S. Department of Energy under Contract No. DE-AC03-76SFOOO98( to P. N. Ross), as well as by the U.S. Office of Naval Research and the National Science Foundation (to M. J. Weaver).

PY - 1995/1

Y1 - 1995/1

N2 - 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.

AB - 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.

KW - FTIR

KW - Pt-Ru alloys

KW - electrocatalysis

KW - formic acid

KW - methanol

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VL - 40

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JO - Electrochimica Acta

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IS - 1

ER -

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

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