CO Adsorption on Platinum Electrodes

Cuesta, Ángel; Gutiérrez, C.

doi:10.1002/9780470929421.ch10

Cited by 7 publications

(9 citation statements)

References 83 publications

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“…The electrochemical behavior of the Pt/CO system has received a great deal of attention during the last five decades by numerous researchers worldwide. − The adsorption and oxidation reaction of CO serves as a testing reaction in surface electrochemistry, with many insights in the field of electrocatalysis, especially those concerning the assignment of active sites, having been obtained by employing the Pt/CO system as a model. − However, the vast majority of studies of the adsorption and oxidation of CO on model stepped Pt surfaces have been conducted using acid media. In particular, the application of spectro-electrochemical techniques to study the Pt/CO system using stepped Pt single crystals in alkaline media has received little attention.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of CO Binding Sites on Stepped Pt Single Crystal Electrodes in Alkaline Solutions by in Situ FTIR Spectroscopy

et al. 2019

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The site geometry preference of CO binding on stepped Pt single crystals in alkaline solution was investigated by in situ FTIR spectroscopy. The surfaces of the Pt single crystals consisted of different width (111) terraces, interrupted by ( 110) or (100) monoatomic steps.Experiments carried out with CO adsorbed exclusively on the top of the steps revealed that only linearly bonded CO formed on the (110) steps, while two CO binding geometries (linear and bridge) were observed on the (100) steps. On one hand, for CO adsorbed only on the steps, the positions of the bands corresponding to linearly bonded CO were similar, regardless of the density of steps, suggesting the existence of an interaction between CO ads only along the line of the steps. On the other hand, for full CO coverage, the CO stretching frequencies and the geometry of bound CO were sensitive to the width of the (111) terraces and the step orientations. Consequently, the CO binding sites favored linearly bonded CO for surfaces consisting of shorter (111) terraces and (110) steps. Bridge-bonded CO was favored on surfaces consisting of shorter (111) terraces interrupted by (100) steps. In order to understand the origin of the preference of CO binding sites, the results were compared to the corresponding behavior in acid media, which revealed that in addition to the effect inherent to the Pt surface, the charge on the metal side in an aqueous environment should be taken into consideration.The analysis suggested that the CO adlayers formed at full coverage in acidic and alkaline media had different structures. On the other hand, the structure of the layer of CO adsorbed only at steps was independent of pH.

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Section: Introductionmentioning

confidence: 99%

Monitoring of CO Binding Sites on Stepped Pt Single Crystal Electrodes in Alkaline Solutions by in Situ FTIR Spectroscopy

et al. 2019

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“…This is almost correct, but it does not always work, as will be discussed later 14 . Interestingly, this makes the Pt/CO system very useful for serendipitous discovery, as occurred with the discovery of CO pre-oxidation 15 .…”

Section: Introductionmentioning

confidence: 99%

“…14 Interestingly, this makes the Pt/CO system very useful for serendipitous discovery, as it occurred with the discovery of CO preoxidation. 15 In CO stripping experiments, the CO preoxidation can be considered an ignition process that frequently appears as a voltammetric small wave in the early stage, or a preignition of the electro-oxidation reaction of the CO ads layer. When the preoxidation peak appears, it precedes one or more major oxidation peaks, and it is not difficult to differentiate between one and the other.…”

Section: Introductionmentioning

confidence: 99%

Surface Defects as Ingredients That Can Improve or Inhibit the Pathways for CO Oxidation at Low Overpotentials Using Pt(111)-Type Catalysts

et al. 2020

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All scientific reports regarding the electro-oxidation of CO on Pt, without exception, show that this reaction is favored on Pt surfaces rich in defects. In fact, "ordinary" or simple CO pre-oxidation is a typical process of surface defected catalysts, obeying the conditions of a full COads layer formed at suitably low potentials, such as those of the hydrogen under-potential deposition (HUPD) region. Among the Pt(111)-type surfaces, non-defected Pt(111) has the lowest catalytic activity for CO electro-oxidation. As a novelty, this paper reports that an unusual CO pre-oxidation appears on a non-defected Pt(111) surface, depending on the COads layer preparation, that is, for a COads layer prepared by cooling the flame annealed Pt(111) electrode in a CO atmosphere. The magnitude of this unusual CO pre-oxidation decreases as the Pt surface becomes rich in steps/defects, and using stepped surfaces, this unusual stage of CO electro-oxidation at low overpotentials is revealed to be connected with long-range order on the (111) plane. Interestingly, both "ordinary" and unusual CO pre-oxidations take place on the (111) terrace domains, but only "ordinary" CO pre-oxidation is favored on surfaces rich in defects. We propose a mechanism of indirect participation of the steps/defects in catalysis, according to which, at low overpotentials, steps/defects on the surface act as ingredients that can improve or inhibit the pathways for the CO electro-oxidation reaction, but do not serve as the most active sites themselves. Therefore, at least on extended platinum

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“…However, DAMFCs are suitable candidates for applications in portable/lower-power devices. Thus, a careful design of the electrocatalyst to lower the Pt loading in the DAMFCs and, consequently, their overall cost while maintaining high power output and stability is the main challenge. , …”

Section: Introductionmentioning

confidence: 99%

“…Thus, a careful design of the electrocatalyst to lower the Pt loading in the DAMFCs and, consequently, their overall cost while maintaining high power output and stability is the main challenge. 3,10 Several strategies are being widely investigated to address one or all of the problems mentioned above. As the electrocatalytic performances of platinum-free anodes are still far behind those of Pt-based electrocatalysts, nanoscale engineering of supported Pt is a promising solution.…”

Section: Introductionmentioning

confidence: 99%

Two-Step Dry Synthesis of Binderless 3D Low Pt-Loading Electrocatalysts for Direct Alkaline Methanol Fuel Cell Anodes

Pajootan

Coulombe

Omanovic

2021

ACS Appl. Energy Mater.

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Three-dimensional (3D) porous electrocatalysts of low platinum loading were synthesized by gas-phase pulsed laser ablation (PLA) and deposited on multiwalled carbon nanotubes (MWCNTs) directly grown on a stainless steel mesh current collector by catalyst-free chemical vapor deposition (Pt/MWCNT/SS). The performance of the developed electrocatalysts was evaluated for the methanol oxidation reaction (MOR). The PLA chamber pressure and ablation time were optimized to achieve the highest methanol oxidation current per Pt loading and electrochemically active surface area while maintaining structural stability. The most robust electrocatalyst, obtained with PLA at 10–5 Torr for 5 min, exhibited a 50% higher methanol oxidation current compared to the commercial Pt/C with similar Pt loading. In addition, it showed the lowest loss of active sites after stability tests while maintaining its structural integrity. Increasing the electrolyte temperature from 0 to 80 °C significantly improved the methanol oxidation current on Pt/MWCNT/SS by 13 times compared to 5.8 times for Pt/C. Electrochemical impedance spectroscopy confirmed the faster kinetics of MOR and accelerated oxidation of adsorbed CO on the surface of the Pt/MWCNT/SS relative to the Pt/C.

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CO Adsorption on Platinum Electrodes

Cited by 7 publications

References 83 publications

Monitoring of CO Binding Sites on Stepped Pt Single Crystal Electrodes in Alkaline Solutions by in Situ FTIR Spectroscopy

Monitoring of CO Binding Sites on Stepped Pt Single Crystal Electrodes in Alkaline Solutions by in Situ FTIR Spectroscopy

Surface Defects as Ingredients That Can Improve or Inhibit the Pathways for CO Oxidation at Low Overpotentials Using Pt(111)-Type Catalysts

Two-Step Dry Synthesis of Binderless 3D Low Pt-Loading Electrocatalysts for Direct Alkaline Methanol Fuel Cell Anodes

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