The Role of Surface Oxides in the Electrooxidation of Methanol, Formic Acid and CO on Pt, Ru and Codeposited Pt‐Ru

Frelink, T; Visscher, Whm Wil; Cox, AP; Veen, van Jar Rob

doi:10.1002/bbpc.19961000511

Cited by 15 publications

(23 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on their results the authors concluded that under fuel cell operating conditions, the presence of a metallic Ru phase, which is covered by a weakly bonded Ru oxidation state precursor, e.g., a-Ru-OH species, is a prerequisite for an effective CH 3 OH electro-oxidation catalysis. This is in agreement with reports by Frelink et al, 9,10 who employed in situ electrochemical ellipsometry and quartz crystal microbalance measurements to study the influence of methanol on the Ru oxide formation reaction. Other work has involved a more demanding technique, namely X-ray adsorption near-edge structure ͑XANES͒ spectroscopy.…”

Section: ͓4͔supporting

confidence: 92%

“…[4][5][6] The nature of the most active form of Ru assisting in the CH 3 OH electro-oxidation reaction to CO 2 has attracted a certain amount of discussion in the literature. [7][8][9][10] It has been suggested that catalysts consisting of two phases, namely, Pt and hydrous Ru oxide ͑RuO x H y ͒, are more active than PtRu alloy catalysts, i.e., Pt 0 Ru 0 . 7 Kim et al 8 carried out X-ray photoelectron spectroscopy ͑XPS͒ experiments involving immediate transfer of the electrodes that consisted of Ru and RuO 2 nanoparticles deposited on Pt͑111͒ surfaces to an ultrahigh-vacuum chamber.…”

Section: ͓4͔mentioning

confidence: 99%

See 1 more Smart Citation

Active Form of Ru for the CH[sub 3]OH Electro-oxidation Reaction

Bock

Collier

MacDougall

2005

J. Electrochem. Soc.

View full text Add to dashboard Cite

In this work, unsupported Pt∕Ru catalysts are used to address the issue of Ru oxide involvement during the methanol oxidation reaction, from the point of view of both Ru “oxidation state” (metal vs oxide) and amount of Ru oxide. It is shown that a simple electrochemical method is useful as in situ probe for the Ru oxidation state. The method also yields insight into the Pt to Ru site distribution of the catalyst surface. The results indicate that the electrochemical formation of reversibly reducible Ru oxides is effectively suppressed in CnormalH3OH solutions, most probably because of its involvement in the anodic oxidation reaction to CnormalO2 . In the case of PtRu alloys that consist of surfaces of well-distributed Pt to Ru sites, Ru oxides are not detected on this surface for CnormalH3OH concentrations greater than 0.1M . It is also shown that the electrochemical formation of Ru oxides at the potential of interest prior to the CnormalH3OH oxidation reaction deenhances the catalyst activity for CnormalH3OH oxidation. However, the experiments suggest the deenhancement is low ( <5% at 0.6 and <15% at 0.8V vs the reversible hydrogen electrode) and only observed at potentials equal to or more positive than 0.6V .

show abstract

Section: ͓4͔supporting

confidence: 92%

Section: ͓4͔mentioning

confidence: 99%

Active Form of Ru for the CH[sub 3]OH Electro-oxidation Reaction

Bock

Collier

MacDougall

2005

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…10(B)] shows a more rapid increase; however, here again the decrease in frequency occurs at lower potential than the peak maximum. In ellipsometric measurements [15] we found also a significant change of the optical parameter D in the presence of CO adsorbate, but the adsorbate oxidation peak here coincides with a distinct change in D. It is remarkable that in the mass-balance measurements the main peak of the CO oxidation do not coincide with a distinct change in the frequency; moreover, already some mass decrease occurs before the CO oxidation starts. Apparently a non-electrochemical active species, most likely water, is desorbed in the low potential range, in contrast with a CO-free surface where the mass increases with potential.…”

Section: W Visscher Et Al 542mentioning

confidence: 60%

“…We wanted to apply the EQCM method for a further investigation of CO adsorbed on Pt, in particular, to find out whether water is co-adsorbed with CO. With ellipsometry an adsorbed CO layer was clearly observed [15], but its composition could not be established. For proper evaluation of the PtCOads system detailed knowledge of the adsorption behaviour of Pt itself is required.…”

Section: W Visscher Et Al 534mentioning

confidence: 94%

Electrochemical quartz crystal microbalance measurements of CO adsorption and oxidation on Pt in various electrolytes

Visscher

Gootzen

Cox

et al. 1998

Electrochimica Acta

Self Cite

View full text Add to dashboard Cite

Abstract-The adsorption behaviour of Pt was investigated with the electrochemical quartz microbalance during potential scanning in acid electrolytes. From the mass increase with potential it is concluded that in the potential range of hydrogen desorption and double layer both water and anions are adsorbed in H2SO4 and H3PO4, whereas in HClO4 there is only adsorption of water molecules. The mass changes in the oxygen region indicate that anions are included in the oxide layer. The Pt/COads system was studied in H2SO4, HClO4 and H3PO4. The presence of adsorbed CO is observed as a mass increase with respect to the CO-free system. The results show that water is adsorbed on top of the adsorbed CO layer at low potentials. Moreover, it can be concluded from the mass-balance data that water molecules are attached to the hydrogen monolayer at 0.03 V vs R.H.E. in sulfuric and perchloric acid, but not in phosphoric acid. 7 1997

show abstract

“…5,10,[37][38][39] As seen in Fig. 5, the peak potential continues to shift to more negative values as the Ru coverage is increased, unlike the reports by Frelink et al 40 and Lee and Bergens 6 who found that increasing the surface coverage of the Ru beyond 15% provided no further reduction in the peak potential for CO electrooxidation. The results reported here are more consistent with those of Gasteiger et al 5 who found that the lowest CO electrooxidation potentials were obtained with Ru rich bulk PtRu alloys.…”

Section: Resultsmentioning

confidence: 92%