Mechanisms of the Oxidation of Carbon Monoxide and Small Organic Molecules at Metal Electrodes

Koper, Marc T. M.; Lai, Stanley C. S.; Herrero, Enrique

doi:10.1002/9780470463772.ch6

Cited by 82 publications

(71 citation statements)

References 151 publications

(163 reference statements)

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“…The traces of H 2 O on the Pt electrode surface may react with Pt–O to form Pt–OH and the surface-bonded OH constitutes the oxygen donor reacting with surface-bonded CO to form CO 2 . 38 Due to the hydrophobicity of [C 4 mpy][NTf 2 ], the amount of water dissolved within the bulk [C 4 mpy][NTf 2 ] is, however, essentially negligible in these experiments (Table S2 † ). Thus, the superoxide reacts predominantly with CO 2 rather than with water.…”

Section: Resultsmentioning

confidence: 96%

“…S6, † the time constant ( τ , the time required for current to decay to its 1/ e value; i.e. , ~37% of the maximum current) obtained from a potential step experiment (from 0.0 V to 0.9 V in 100% air) is 6 s. In order to minimize the double layer charging current, 38 we measured the methane oxidation or oxygen reduction current at 300 s ( i.e. , 50 τ ).…”

Section: Resultsmentioning

confidence: 99%

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Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Wang

Guo

Baker

et al. 2014

Analyst

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Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample matrix and allows for the elimination of several types of random and systematic errors in the detection. We have also validated this IL-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single- and double-potential step chronoamperometry.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Wang

Guo

Baker

et al. 2014

Analyst

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“…Although some questions dealing with its reaction mechanism are still under discussion, including the nature and role of the active species [73][74][75][76][77][78] or the effect of the pH on the reaction mechanism [79][80][81][82], it is well established that, on Pt surfaces, the reaction is structure-sensitive, the Pt (100) being the most active (in the absence of CO poisoning), but it is also the most poisoned [71,83,84]. This surface structure sensitivity has been also demonstrated on the nanoscale using different shape-controlled Pt nanoparticles [7,33,41,85,86].…”

Section: Formic Acid Electrooxidationmentioning

confidence: 99%

Influence of the metal loading on the electrocatalytic activity of carbon-supported (100) Pt nanoparticles

Vidal‐Iglesias

Montiel

Solla-Gullón

2015

J Solid State Electrochem

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The influence of the metal loading (i.e. interparticle distance) of shape-controlled Pt nanoparticles on their electrocatalytic properties is evaluated for the first time. For this purpose, carbon-supported cubic Pt nanoparticles (~17 nm) with different metal loadings were prepared, characterized and electrochemically tested. To avoid differences in particle size and shape/surface structure of the Pt nanoparticles between samples, all samples used in this work were prepared from a single batch. The surface structure of the Pt nanoparticles was evaluated through the so-called hydrogen region and showed a preferential (100) orientation. Interestingly, the electroactive surface area of the samples, estimated both from the H or CO stripping processes, was directly proportional to the total Pt mass, independently of the metal loading. The CO stripping profile was also found to be unaffected by the metal loading. However, for ammonia and formic acid electrooxidation, the activity obtained was dependent on the metal loading. For ammonia oxidation, the optimal loading was found to be about 20-30 wt%. Nevertheless, this trend may be altered by different factors including (i) active surface area, (ii) metal loading and (ii) thickness of the catalytic layer. For formic acid electrooxidation, the results obtained showed a clear decrease of the activity for increasing metal loadings which is explained in terms of formic acid consumption on the top layers of the catalyst.

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“…[31][32][33][34] CO monolayer oxidation is also known to be structure sensitive on Pt surfaces but with a minor structural sensitivity than ammonia electro-oxidation. [22,34,35] In fact, in case of Pt nanoparticles, all surface sites contribute to the reaction although the CO oxidation peak coming from the (100) terraces is relatively wellseparated from the others and appears at a higher potential value. [11,36,37] Figure 5 shows the CO stripping voltammograms shaped Pt nanoparticles, it was established that the second of these two peaks is ascribed to the presence of (100) surface domains.…”

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Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

et al. 2014

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The increasing number of applications for shape-controlled metal nanoparticles leads to the need of easy, cheap and scalable methodologies. In this communication we report, the synthesis of (100) preferentially oriented platinum (Pt) nanoparticles with 9 nm particle size using a water-in-oil microemulsion method. The specific surface structure of the nanoparticles is induced by the presence of H2SO4 in the water phase of the microemulsion. Interestingly, the results here reported will show how increasing amounts of H2SO4 lead to the formation of Pt nanoparticles containing a higher amount of (100) sites on their surface. This preferential surface orientation has been confirmed electrochemically by using the so-called hydrogen adsorption/desorption process. In addition, TEM measurements have confirmed the presence of cubic-like Pt nanoparticles. Finally, the electrocatalytic properties of the Pt nanoparticles have been evaluated towards ammonia and CO electro-oxidations as (100) structure sensitive reactions.Several methodologies for shape control of metal nanoparticles have been developed in the past decade with the main objective of controlling the specific arrangements of the atoms at their surface, that is, their surface structure. [1][2][3][4] In this way, as widely demonstrated with metal single crystals as model electrodes, the catalytic properties of the metal nanostructures can be tuned and optimised for a particular reaction. Among others, and due to its unique catalytic properties, Pt nanoparticles have been the focus of numerous studies from which their remarkable surface structure sensitivity has been illustrated and discussed for several reactions of interest. [1,5] On the other hand, from a more applied point of view, it would be desirable to have a simple, fast and economically viable methodology for the preparation of such shapecontrolled metal nanoparticles to be then scalable for large scale applications. However, most of the developed synthetic routes do not fulfil with these requirements and consequently, the scalability still remains a challenge. In this regard, in a very recent publication, we have extended the use of water-in-oil microemulsions, traditionally employed for the preparation of metal nanoparticles with controlled atomic composition and size, for the preparation of shape-controlled Pt nanoparticles. In particular, we have reported that the addition of determined amounts of HCl in the water phase of the microemulsion led to the formation of Pt nanoparticles with a bell-shaped preferential (100) surface structure with a maximum of the (100) character at about 25% of HCl.[6] This approach opens new possibilities in terms of scalability because the handling of the water-in-oil microemulsions is easy, fast, economic and frequently performed at room temperature. In this communication, we will show that H2SO4 can be also used as effective (100) surface modifier during the preparation of Pt nanoparticles in microemulsion (see experimental section for details). The resulting Pt nanopart...

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Mechanisms of the Oxidation of Carbon Monoxide and Small Organic Molecules at Metal Electrodes

Cited by 82 publications

References 151 publications

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Influence of the metal loading on the electrocatalytic activity of carbon-supported (100) Pt nanoparticles

Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

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Mechanisms of the Oxidation of Carbon Monoxide and Small Organic Molecules at Metal Electrodes

Cited by 82 publications

References 151 publications

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Influence of the metal loading on the electrocatalytic activity of carbon-supported (100) Pt nanoparticles

Synthesis and Electrocatalytic Properties of H2SO4‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

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Product

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Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion