Electrocatalysis and transport effects on nanostructured Pt/GC electrodes

Lindström, Rakel Wreland; Seidel, Y.E.; Jusys, Z.; Gustavsson, Martin; Wickman, Björn; Kasemo, Bengt Herbert; Behm, R. Jürgen

doi:10.1016/j.jelechem.2009.04.034

Cited by 42 publications

(66 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…These findings can be interpreted as follows 1) contribution of CO ad oxidation to the overall CO 2 formation rate is relatively higher on the continuous Pt film, compared to discontinued Pt nanostructures, in agreement with the corresponding active surface (Table 1), 2) the probability for readsorption and further oxidation of formic acid to CO 2 increases according to the desorption-readsorption-reaction model. [16,17] Coupling Effects for Synchronous Oscillating Behaviour of Nanostructured Electrodes…”

Section: Effect Of Pt Nanostructurementioning

confidence: 99%

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

et al. 2010

View full text Add to dashboard Cite

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.

show abstract

“…In practical cases, highly dispersed Pt catalysts with large surface areas are extremely important to increase the electrocatalytic reactivity [2][3][4]. The information on the electrochemically active surface area (ECA) of such Pt-based electrocatalysts is essential to derive the specific activity for evaluation and comparison of the different catalysts from various sources [4][5][6][7][8][9]. This is one of the prerequisites to understand the relationship between the catalytic activity and their structure/composition, which are the basis for rational design of highly efficient electrocatalysts for PEMFCs and other electrochemical processes.…”

Section: Introductionmentioning

confidence: 99%

Determining the Active Surface Area for Various Platinum Electrodes

et al. 2011

View full text Add to dashboard Cite

Various methods, i.e., the adsorption/stripping of adsorbed probe species, such as hydrogen (H), copper (Cu), and carbon monoxide (CO), oxygen and hydroxide (O/ OH), potentiostatic CO/H displacement as well as double layer capacitance are exploited to evaluate the electrochemically active surface areas (ECAs) of platinum (Pt) foils, chemically deposited Pt thin film, and carbon-supported Pt nanoparticle electrodes. For the relatively smooth Pt electrodes (roughness factor < 3), the measurements from the stripping of H, Cu, and CO adlayers and CO/H displacement at 0.08 V (vs. RHE) give similar ECAs. With the increase of the surface roughness, it was found that the ECAs deduced from the different methods have the order of CO/H displacement less than the stripping of under potential deposition (UPD) Cu monolayer less than the stripping of the UPD-H adlayer. Possible origins for the discrepancies as well as the applicability of all the abovementioned methods for determining ECAs of various Pt electrodes are discussed, and the UPD-Cu method is found to be the most appropriate technique for the determination of ECAs of Pt electrodes with high roughness factors or composed of nanoparticles with high dispersion.

show abstract

Electrocatalysis and transport effects on nanostructured Pt/GC electrodes

Cited by 42 publications

References 67 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

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

Determining the Active Surface Area for Various Platinum Electrodes

Contact Info

Product

Resources

About