Impedance plane display of a reaction with an adsorbed intermediate

The high theoretical energy density of lithium−oxygen batteries brings the promise of higher performance than existing batteries, but several technological problems must be addressed before actual applications are made possible. Among the difficulties to be faced is the slow oxygen reduction reaction (ORR), which requires a suitable choice of catalysts and electrolytic solution. This can only be achieved if the kinetics and mechanism of this reaction are known in detail. In this study, we determined the rate constants for each elementary step of ORR for a platinum electrode in 0.1 mol•L −1 LiClO 4 /1,2-dimethoxyethane (DME), using a kinetic model in the frequency domain. We found that the energy storage capacity of lithium−air batteries can be increased by converting a large amount of lithium superoxide into lithium peroxide during the electrochemical step in comparison with chemical disproportionation. The mechanisms for ORR were supported by data from an electrochemical quartz crystal microbalance (EQCM): ORR could be distinguished from parasitic reactions induced by solvent degradation, and agglomerates of Li x O 2 (1 ≤ x ≤ 2) were adsorbed on the electrode. The rate-limiting step for ORR was the electron transfer to the oxygen molecules strongly adsorbed onto platinum sites, particularly as a large amount of reaction product (Li 2 O 2 ) adsorbed onto the electrode. Even though Pt sheets are likely to be impracticable for real applications due to their low surface area, they were useful in making it possible to determine the kinetics of ORR steps. This can now be employed to devise more involved electrodes, such as those containing dispersed Pt nanoparticles.

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“…In the transient state during the perturbation ac potential, Taylor expansion helps to express the step rates as 42,43 …”

Section: ■ Kinetic Modelmentioning

confidence: 99%

Investigating the Kinetic Mechanisms of the Oxygen Reduction Reaction in a Nonaqueous Solvent

et al. 2014

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“…This indicates that the overall methanol oxidation rate is faster [59]. The ''pseudoinductive'' behaviour means that the current signal follows a voltage perturbation with a phase delay [60], and it is generally associated with consecutive heterogeneous reactions involving adsorbed intermediates [61,62]. This pseudo-inductive behaviour was observed firstly during corrosion tests; it was caused by pitting in the protection layer and subsequent corrosion of the metal through the holes of the protection layer.…”

Section: Microemulsion-synthesized Pt/ru Nanoparticlesmentioning

confidence: 99%

Deposition of clusters and nanoparticles onto boron-doped diamond electrodes for electrocatalysis

et al. 2006

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Metal and metal oxide particles and nanoparticles, differing from each other by their nature and synthesis technique, were deposited onto boron-doped diamond (BDD) thin film electrodes. The applicability in electrocatalysis of thermally decomposed IrO 2 and Au nanoparticles, electrodeposited Pt particles, dendrimer-encapsulated Pt nanoparticles (Pt DENs) and microemulsion-synthesized Pt/Ru nanoparticles was studied, once deposited on BDD substrate. In all cases, the electrochemical response of the composite electrodes could be solely attributed to the supported particles. All the particles, with the exception of Pt DENs, exhibited electrocatalytic activity. Pt DENs inactivity has been attributed to insufficient removal of the dendrimer polymer matrix. It was concluded that the BDD electrode is a suitable substrate for the electrochemical investigation of supported catalytic nanoparticles.

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“…According to Kendig [17], it is caused by a non linear frequency response resulting from irreversible desorption of the adsorbed intermediates. Armstrong et al [18] and Epelboin et al [19] have proposed methods to model pseudo inductive frequency responses and extract corrosion rate information from ac impedance data. In principle, an electrochemical process may be modeled by equivalent electrical circuit elements, such as, resistors, capacitors and inductors.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Passive Film Properties and Pitting Resistance of AISI 316 in Aqueous Ethanoic Acid Containing Chloride Ions using Electrochemical Impedance Spectroscopy(EIS)

Mahato

Singh

2011

Port. Electrochim. Acta

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The structure and properties of the passive film formed on the surface of AISI 316 stainless steel in aqueous ethanoic acid have been investigated using EIS. Experiments were carried out at 30 ºC in different concentrations of ethanoic acid. Effects on the film properties due to the change of electrode potential, exposure durations and addition of chloride ions to the electrolyte were also studied. Impedance parameters were determined using simple model and equivalent electrical circuit. Results suggest the formation of multilayered passive film on the steel surface. The film possessed dual structure. Inner layers were thin and compact, whereas the outer layer was porous and defective. The measured capacitive behavior was of non ideal nature and hence replaced by constant phase element or CPE. Formation of the passive film and the change in its structure has been explained using impedance parameters.

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Impedance plane display of a reaction with an adsorbed intermediate

Cited by 408 publications

References 9 publications

Investigating the Kinetic Mechanisms of the Oxygen Reduction Reaction in a Nonaqueous Solvent

Investigating the Kinetic Mechanisms of the Oxygen Reduction Reaction in a Nonaqueous Solvent

Deposition of clusters and nanoparticles onto boron-doped diamond electrodes for electrocatalysis

Investigation of Passive Film Properties and Pitting Resistance of AISI 316 in Aqueous Ethanoic Acid Containing Chloride Ions using Electrochemical Impedance Spectroscopy(EIS)

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