Stability and ORR performance of a well-defined bimetallic Ag70Pt30/Pt(111) monolayer surface alloy electrode – Probing the de-alloying at an atomic scale

Beckord, Stephan; Brimaud, Sylvain; Behm, R. Jürgen

doi:10.1016/j.electacta.2017.10.146

Cited by 16 publications

(13 citation statements)

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“…Furthermore we suggested that these structures could also contain Ru atoms, resulting from re‐deposition of dissolved Ru on the newly formed Pt structures. Based on a recent study on the dissolution of Ag from AgPt/Pt(111) surface alloys, we suggest, however, that with a flow‐cell set‐up redeposition of Ru atoms is unlikely since it is more probable that dissolved species are transported away from the electrode with the flowing electrolyte [15] . The positive‐going potential scans for the COOR (red) and MOR (blue) on both stable and restructured electrodes are shown in Figure 4 c).…”

Section: Figurementioning

confidence: 91%

“…Based on a recent study on the dissolution of Ag from AgPt/Pt(111) surface alloys, we suggest, however, that with a flow-cell set-up redeposition of Ru atoms is unlikely since it is more probable that dissolved species are transported away from the electrode with the flowing electrolyte. [15] The positive-going potential scans for the COOR (red) and MOR (blue) on both stable and restructured electrodes are shown in Figure 4 c). In both cases, the restructured electrodes are more active than the stable counterparts at potentials > 0.5 V.…”

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confidence: 99%

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Bifunctional versus Defect‐Mediated Effects in Electrocatalytic Methanol Oxidation

2021

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The most prominent and intensively studied anode catalyst material for direct methanol oxidation fuel cells consists of a combination of platinum (Pt) and ruthenium (Ru). Classically, their high performance is attributed to a bifunctional reaction mechanism where Ru sites provide oxygen species at lower overpotential than Pt. In turn, they oxidize the adsorbed carbonaceous reaction intermediates at lower overpotential; among these, the Pt site‐blocking carbon monoxide. We demonstrate that well‐defined Pt modified Ru(0001) single crystal electrodes, with varying Pt contents and different local PtRu configurations at the surface, are unexpectedly inactive for the methanol oxidation reaction. This observation stands in contradiction with theoretical predictions and the concept of bifunctional catalysis for this reaction. Instead, we suggest that pure Pt defect sites play a more critical role than bifunctional defect sites on the electrodes investigated in this work.

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Section: Figurementioning

confidence: 91%

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confidence: 99%

Bifunctional versus Defect‐Mediated Effects in Electrocatalytic Methanol Oxidation

2021

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“…For Ag contents below 50%, a remarkable stabilization against electrochemical dissolution up to 0.95 V versus RHE was observed . The ORR at such alloy surfaces was studied as well . A reduced ORR overpotential compared to Pt(111) was obtained for these surface alloys (Figure B) .…”

Section: Bimetallic Catalysts and “Chemical Contrast”mentioning

confidence: 97%

“…Recently, such well‐defined model systems have been applied, after STM characterization in vacuum, for electrochemical experiments . For instance, it was shown that for Pt x Ru 1− x monolayers on Ru(0001), surfaces with a larger amount of Pt‐rich trimers show a larger ORR activity corresponding to an overpotential reduction by 70 mV compared to Pt(111), while surfaces dominated by Ru‐rich trimers have a much lower activity .…”

Section: Bimetallic Catalysts and “Chemical Contrast”mentioning

confidence: 99%

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Electrochemical Scanning Probe Microscopies in Electrocatalysis

et al. 2018

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surface coordination, strain effects, [6][7][8][9] ligand effects, [10,11] ensemble effects, [12] and the electrolyte composition. [13] A detailed understanding of these effects requires experimental and computational procedures to investigate the working mechanisms of the electrocatalysis. Ideally, atomically resolved topographic and chemical information of the catalyst surface under reaction conditions is required. Transmission electron microscopy (TEM) has been reported to be capable of in operando investigation of catalyst structures while catalytic reactions are taking place. [14] However, the instrumentation utilized for such purpose has very strong restrictions and realistic operating conditions cannot be easily applied so far. Alternatively, scanning probe microscopies (SPMs) and electrochemical scanning probe microscopies (EC-SPMs) are able to perform structural measurements of catalytic systems under reaction conditions with resolution down to atomic scales. Normally, EC-SPMs, for instance electrochemical scanning tunneling microscopy (EC-STM), electrochemical atomic force microscopy (EC-AFM), and scanning electrochemical potential microscopy (SECPM), can provide structural information on the solid side of the electrode/electrolyte interface at the atomic level for conductive samples (EC-STM is limited in the case of semi/nonconductive samples). However, these techniques usually lack the capability of chemical sensitivity, ultrahigh resolution reactivity monitoring, and probing the property of the electrolyte side of the interface. One well-developed exception is the scanning electrochemical microscopy (SECM), which will also be discussed in detail within this review. Additionally, SECM and related methods permit gleaning information about the electrolyte side of the electrochemical interface. However, the resolution of SECM and related methods is limited by the size of the SECM-probe and the working principle of SECM.In this review, first a very brief overview on electrocatalysis and on the importance of model substrates for understanding the fundamental underlying principles is given. Thereafter, the operational principle of different SPM techniques is summarized. The main focus of the work lies then on the application of the techniques to study phenomena important for electrocatalysis, including surface topography and adsorption processes. Within that context, also the application of room Improvements toward highly efficient electrochemical energy conversion require a detailed understanding of the underlying electrochemical processes at electrified solid-liquid interfaces. In situ and in operando studies by means of electrochemical scanning probe microscopy (EC-SPM) have become indispensable experimental tools due to their capability of resolving surface topography down to the atomic level even within the harsh environment of electrolytes. EC-SPM methodologies have thus contributed tremendously to the current understanding of electrocatalysis. In this review article, recent achievements in complement...

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Methods and Instruments | Differential Electrochemical Mass Spectrometry

Jusys,

Behm

2025

Encyclopedia of Electrochemical Power Sources

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Stability and ORR performance of a well-defined bimetallic Ag70Pt30/Pt(111) monolayer surface alloy electrode – Probing the de-alloying at an atomic scale

Cited by 16 publications

References 54 publications

Bifunctional versus Defect‐Mediated Effects in Electrocatalytic Methanol Oxidation

Bifunctional versus Defect‐Mediated Effects in Electrocatalytic Methanol Oxidation

Electrochemical Scanning Probe Microscopies in Electrocatalysis

Methods and Instruments | Differential Electrochemical Mass Spectrometry

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