Catalytic Effect of Platinum on Oxygen Reduction An Ab Initio Model Including Electrode Potential Dependence

Anderson, Alfred B.; Albu, Titus V.

doi:10.1149/1.1394046

Cited by 195 publications

(232 citation statements)

References 38 publications

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“…3 This activated HOO* species decomposes to adsorbed O* and HO* species with its activation barrier small (i.e., 0.06 eV) according to previous DFT studies. 3,24 The reduction of HOO* may lead to H 2 O by the formation of hydrogen peroxide (H 2 O 2 *) intermediate (i.e., a series pathway) 3,21,55 or by directly forming H 2 O and adsorbed O*. 2,3,55 Although the former was suggested to be the lower energy pathway, 55 it has generally been accepted that the H 2 O 2 * intermediate is unstable and thus readily dissociates homolytically into HO* + HO* species.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of the Oxygen Reduction Reaction on Defective Graphene-Supported Pt Nanoparticles from First-Principles

2012

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The mechanisms of the oxygen reduction reaction (ORR) on defective graphene-supported Pt 13 nanoparticles have been investigated to understand the effect of defective graphene support on the ORR and predict details of ORR pathways. We employed density functional theory (DFT) predictions using the projector-augmented wave (PAW) method within the generalized gradient approximation (GGA). Free energy diagrams for the ORR over supported and unsupported Pt 13 nanoparticles were constructed to provide the stability of possible intermediates in the electrochemical reaction pathways. We demonstrate that the defective graphene support may provide a balance in the binding of ORR intermediates on Pt 13 nanoparticles by tuning the relatively high reactivity of free Pt 13 nanoparticles that bind the ORR intermediates too strongly subsequently leading to slow kinetics. The defective graphene support lowers not only the activation energy for O 2 dissociation from 0.37 to 0.16 eV, but also the energy barrier of the rate-limiting step by reducing the stability of HO* species. We predict the ORR mechanisms via direct four-electron and series two-electron pathways. It has been determined that an activation free energy (0.16 eV) for O 2 dissociation from adsorbed O 2 * at a bridge site on the supported Pt 13 nanoparticle into O* + O* species (i.e., the direct pathway) is lower than the free energy barrier (0.29 eV) for the formation of HOO* species from adsorbed O 2 * at the corresponding atop site, indicating that the direct pathway may be preferred as the initial step of the ORR mechanism. Also, it has been observed that charge is transferred from the Pt 13 nanoparticle to both defective graphene and the ORR intermediate species.

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Section: Resultsmentioning

confidence: 99%

Mechanisms of the Oxygen Reduction Reaction on Defective Graphene-Supported Pt Nanoparticles from First-Principles

2012

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“…Theoretically, it has been shown that bonding of O 2 , OOH* and H 2 O 2 to Pt surfaces decreases the high activation energies for these outer-sphere reductions [63][64][65], but at the same time increases HO* activation energy [63] and stabilises OH ads and O ads [12,13,[66][67][68][69][70]. Because of that, the formation of OOH ads , compared to O ads + OH ads , would not be stable [67], and so, the reduction of this species, if formed, would occur in the solution side of the interface.…”

Section: Role Of Oh Ads /O Ads In the Orr Dynamics On Pt(111)mentioning

confidence: 99%

Role of oxygen-containing species at Pt(111) on the oxygen reduction reaction in acid media

Gómez–Marín

Feliu

2015

J Solid State Electrochem

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Abstract:The oxygen reduction reaction (ORR) is one of the fundamental reactions in electrochemistry and has been widely studied, but the mechanistic details of ORR still remain elusive. In this work, the role of electrochemical oxygenated species, such as adsorbed hydroxide, OH ads , adsorbed oxygen, O ads , and Pt (111) oxide, PtO, in the ORR dynamics is studied by employing electrochemical techniques, i.e. combining rotating disk mass-transport control with potential sweep rate perturbation. In this framework, a reduction peak at 0.85 V, E ORR , is detected. This peak shows a different electrochemical dynamics than that of Pt (111) oxides. The data analysis suggests that neither OH ads nor O ads are the main bottleneck in the mechanism. Instead, results support the reduction of a soluble intermediate species as the rate determining step in the mechanism. On the other hand, PtO species, which are generated at relatively high potentials, and are responsible of surface disordering, strongly inhibit the ORR as long as they are adsorbed in the electrode surface.

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“…These studies supplied information on each elementary step, such as activation energies, reaction energies, and reversible potentials. Anderson and co-workers [54,55] investigated the activation barrier for each of the following electron transfer steps:…”

Section: Oxygen Reduction Reactionmentioning

confidence: 99%

A general model for air-side proton exchange membrane fuel cell contamination

Shi

Song

et al. 2009

Journal of Power Sources

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. This paper presents a general model for air-side feed stream contamination that has the capability of simulating both transient and steady-state performance of a PEM fuel cell in the presence of air-side feed stream impurities. The model is developed based on the oxygen reduction reaction mechanism, contaminant surface adsorption/desorption, and electrochemical reaction kinetics. The model is then applied to the study of air-side toluene contamination. Experimental data for toluene contamination at four current densities (0.2, 0.5, 0.75 and 1.0 A cm −2 ) and three contamination levels (1, 5 and 10 ppm) were used to validate the model. In addition, it is expected that, with parameter adjustment, this model can also be used to predict performance degradation caused by other air impurities such as nitrogen oxides (NO x ) and sulfur oxides (SO x ). Crown

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Catalytic Effect of Platinum on Oxygen Reduction An Ab Initio Model Including Electrode Potential Dependence

Cited by 195 publications

References 38 publications

Mechanisms of the Oxygen Reduction Reaction on Defective Graphene-Supported Pt Nanoparticles from First-Principles

Mechanisms of the Oxygen Reduction Reaction on Defective Graphene-Supported Pt Nanoparticles from First-Principles

Role of oxygen-containing species at Pt(111) on the oxygen reduction reaction in acid media

A general model for air-side proton exchange membrane fuel cell contamination

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