Transport Effects in the Electrooxidation of Methanol Studied on Nanostructured Pt/Glassy Carbon Electrodes

Seidel, Y.E.; Schneider, Armin; Jusys, Z.; Wickman, Björn; Kasemo, Bengt Herbert; Behm, R. Jürgen

doi:10.1021/la902962g

Cited by 67 publications

(67 citation statements)

References 62 publications

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“…These measurements exhibited a clear correlation between the product distribution and the density of the Pt ultra-microelectrodes, with the relative amount of reaction intermediates in the overall reaction products decreasing with increasing density of catalytically active Pt nanodisks [5,7]. Similar trends have been reported for the oxidation of formaldehyde [10] and methanol [11] on these nanostructured Pt/GC electrodes. The same is true for the dependency of the product yields on the catalyst loading in the case of a single large Pt/C electrode, e.g.…”

Section: Introductionsupporting

confidence: 76%

The Role of Reactive Reaction Intermediates in Two‐Step Heterogeneous Electrocatalytic Reactions: A Model Study

Fuhrmann¹,

Zhao²,

Langmach³

et al. 2011

Fuel Cells

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This paper summarises the result of previous experimental investigations of heterogeneous electrocatalytic reactions performed in flow cells which provide an environment with controlled parameters. Measurements of the oxygen reduction reaction in a flow cell with an electrode consisting of an array of Pt nanodisks on a glassy carbon substrate exhibited a decreasing fraction of the intermediate H2O2 in the overall reaction products with increasing density of the nanodisks. A similar result is true for the dependence on the catalyst loading in the case of a supported Pt/C catalyst thin‐film electrode, where the fraction of the intermediate decreases with increasing catalyst loading. Similar effects have been detected for the methanol oxidation.In order to give a possible explanation to the observed effect, we present a model of multistep heterogeneous electrocatalytic oxidation and reduction reactions based on an adsorption‐reaction‐desorption scheme using the Langmuir assumption and macroscopic transport equations. A continuum based model problem in a vertical cross‐section of a rectangular flow cell is proposed in order to explain basic principles of the experimental situation. It includes three model species A, B, C, which undergo adsorption and desorption at a catalyst surface, as well as adsorbate reactions from A to B to C. These surface reactions are coupled with diffusion and advection in the Hagen Poiseuille flow in the flow chamber of the cell. High velocity asymptotic theory and a finite volume numerical method are used to obtain approximate solutions to the model. Both approaches show a behaviour similar to the experimentally observed. Working in more general situations, the finite volume scheme was applied to a catalyst layer consisting of a number of small catalytically active areas corresponding to nanodisks. Good qualitative agreement with the experimental findings is established for this case as well.

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Section: Introductionsupporting

confidence: 76%

The Role of Reactive Reaction Intermediates in Two‐Step Heterogeneous Electrocatalytic Reactions: A Model Study

Fuhrmann¹,

Zhao²,

Langmach³

et al. 2011

Fuel Cells

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“…A few half-cell studies are available on the effect of mass transport upon alcohol oxidation over Pt, but these have concentrated on the utilisation of methanol as a fuel [38,41,42,[47][48][49] with very few studies using ethanol [39,50,51]. Most studies have reported a suppression of the extent of oxidation of methanol on Pt disk electrode with increased mass transport [38,42].…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Effect of Mass Transport on the Electrochemical Oxidation of Alcohols Over Electrodeposited Film and Carbon-Supported Pt Electrodes

et al. 2018

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Electrochemical oxidation of four different alcohol molecules (methanol, ethanol, n-butanol and 2-butanol) at electrodeposited Pt film and carbon-supported Pt catalyst film electrodes, as well as the effect of mass transport on the oxidation reaction, has been studied systematically using the rotating disk electrode (RDE) technique. It was shown that oxidation current decreased with an increase in the rotation rate (ω) for all alcohols studied over electrodeposited Pt film electrodes. In contrast, the oxidation current was found to increase with an increase in the ω for Pt/C in ethanol and n-butanol-containing solutions. The decrease was found to be nearly reversible for ethanol and n-butanol at the electrodeposited Pt film electrode ruling out the possibility of intermediate CO ads poisoning being the sole cause of the decrease and was attributed to the formation of soluble intermediate species which diffuse away from the electrode at higher ω. In contrast, an increase in the current with an increase in ω for the carbon supported catalyst may suggest that the increase in residence time of the soluble species within the catalyst layer, results in further oxidation of these species. Furthermore, the reversibility of the peak current on decreasing the ω could indicate that the surface state has not significantly changed due to the sluggish reaction kinetics of ethanol and n-butanol.

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“…tion [13,14] ). However, pronounced mass transport effects on the reaction selectivity were demonstrated recently for electrocatalytic reactions over nanostructured Pt electrodes [15][16][17][18] deposited onto a planar glassy carbon substrate by employing colloidal lithography techniques. [19,20] On these surfaces, mass transport effects can be assessed in model studies where the reactant delivery to the patterned surface and off-transport of the reaction intermediates/products are varied in a controlled way, thus affecting both reaction activity and selectivity, as probed for several electrocatalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

“…[19,20] On these surfaces, mass transport effects can be assessed in model studies where the reactant delivery to the patterned surface and off-transport of the reaction intermediates/products are varied in a controlled way, thus affecting both reaction activity and selectivity, as probed for several electrocatalytic reactions. [15][16][17][18] Complementary galvanostatic formaldehyde oxidation measurements on these patterned catalysts are the topics herein. Since the galvanostatic oxidation of formaldehyde on continuous electrodes exhibits potential oscillations, [21][22][23][24][25][26] such studies will also yield information about synchronization properties of the array of individual Pt nanostructures (oscillators), that is, whether the array will exhibit a regular concerted oscillatory behavior, or whether the individual oscillators will behave randomly, resulting in a stationary response of the average electrode potential.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory behaviour in Galvanostatic Formaldehyde Oxidation on Nanostructured Pt/Glassy Carbon Model Electrodes

et al. 2010

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The electrocatalytic oxidation of formaldehyde, which results in CO(2) and HCOOH formation, was investigated under galvanostatic conditions on nanostructured Pt/glassy carbon (GC) electrodes fabricated by employing colloidal lithography (CL). The measurements were performed on structurally well-defined model electrodes of different Pt surface coverages under different applied currents (current densities) and at constant electrolyte transport in a thin-layer flow cell connected to a differential electrochemical mass spectrometry (DEMS) setup to monitor the dynamic response of the reaction selectivity under these conditions. Periodic oscillations of the electrode potential and the CO(2) formation rate appear not only for a continuous Pt film, but also for the nanostructured Pt/GC electrodes when a critical current density is exceeded. The critical current density for achieving regular oscillation patterns increased with decreasing Pt nanodisk density. Lower oscillation frequencies of the electrode potential and lower CO(2) formation rate for nanostructured Pt/GC electrodes compared to continuous Pt film at similar applied current densities suggest that transport processes play an essential role. Moreover, from the simple periodic response of the nanostructured electrodes it follows that all individual Pt disks in the array oscillate in synchrony. This result is discussed in terms of the different modes of spatial coupling present in the system: global coupling, migration coupling and mass transport of the essential chemical species, and the coverage of corresponding adsorbates.

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Transport Effects in the Electrooxidation of Methanol Studied on Nanostructured Pt/Glassy Carbon Electrodes

Cited by 67 publications

References 62 publications

The Role of Reactive Reaction Intermediates in Two‐Step Heterogeneous Electrocatalytic Reactions: A Model Study

The Role of Reactive Reaction Intermediates in Two‐Step Heterogeneous Electrocatalytic Reactions: A Model Study

Effect of Mass Transport on the Electrochemical Oxidation of Alcohols Over Electrodeposited Film and Carbon-Supported Pt Electrodes

Oscillatory behaviour in Galvanostatic Formaldehyde Oxidation on Nanostructured Pt/Glassy Carbon Model Electrodes

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