Current status of ab initio quantum chemistry study for oxygen electroreduction on fuel cell catalysts

Shi, Zheng; Zhang, Jiujun; Liu, Zhong‐Sheng; Wang, Haijiang; Wilkinson, David P.

doi:10.1016/j.electacta.2005.07.006

Cited by 143 publications

(95 citation statements)

References 61 publications

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“…In recent years, many theoretical explorations of the ORR mechanism using quantum mechanic methods have been reported, as shown in the review articles [52,53]. These studies supplied information on each elementary step, such as activation energies, reaction energies, and reversible potentials.…”

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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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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“…Because the fundamental microscopic mechanisms involved in oxidation and reduction at electrode surfaces are often unknown and are difficult to determine experimentally, 6 rich scientific opportunities are available for theoretical study. From a technological perspective, practicable first principles calculations could become a vital tool to direct the experimental search for better catalysts with significant potential societal impact: as just one example, economically viable replacement of gasoline powered engines with fuel cells in personal transport systems requires systems operating at a cost of $35/kW, whereas the current cost is $294/kW, 7 due mostly to the expense of platinum-based catalyst materials.…”

Section: -5mentioning

confidence: 99%

Joint density functional theory of the electrode-electrolyte interface: Application to fixed electrode potentials, interfacial capacitances, and potentials of zero charge

2012

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This work explores the use of joint density-functional theory, a new form of density-functional theory for the ab initio description of electronic systems in thermodynamic equilibrium with a liquid environment, to describe electrochemical systems. After reviewing the physics of the underlying fundamental electrochemical concepts, we identify the mapping between commonly measured electrochemical observables and microscopically computable quantities within an, in principle, exact theoretical framework. We then introduce a simple, computationally efficient approximate functional which we find to be quite successful in capturing a priori basic electrochemical phenomena, including the capacitive Stern and diffusive Gouy-Chapman regions in the electrochemical double layer, quantitative values for interfacial capacitance, and electrochemical potentials of zero charge for a series of metals. We explore surface charging with applied potential and are able to place our ab initio results directly on the scale associated with the Standard Hydrogen Electrode (SHE). Finally, we provide explicit details for implementation within standard density-functional theory software packages at negligible computational cost over standard calculations carried out within vacuum environments.

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“…44 Insight into the likelihood of possible pathways can, however, come from quantum chemistry calculations based on density functional theory ͑DFT͒ and ab initio molecular dynamics. 45 The stability of intermediates and the activation energies for proposed individual steps can be approximately calculated. 46 Assuming O 2 adsorption at a dual site, Sidik and Anderson 47 demonstrated by DFT that the rate-determining step is Pt − O 2 + H + + e − → Pt − OOH, in agreement with selected experimental data.…”

Section: Membrane Degradationmentioning

confidence: 99%

Modeling and Simulation of the Degradation of Perfluorinated Ion-Exchange Membranes in PEM Fuel Cells

Shah

Ralph

Walsh

2009

J. Electrochem. Soc.

120

107

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A polymer electrolyte membrane ͑PEM͒ fuel cell model that incorporates chemical degradation in perfluorinated sulfonic acid membranes is developed. The model is based on conservation principles and includes a detailed description of the transport phenomena. A degradation submodel describes the formation of hydrogen peroxide via distinct mechanisms in the cathode and anode, together with the subsequent formation of radicals via Fenton reactions involving metal-ion impurities. The radicals participate in the decomposition of reactive end groups to form carboxylic acid, hydrogen fluoride, and CO 2 . Degradation proceeds through unzipping of the polymer backbone and cleavage of the side chains. Simulations are presented, and the numerical code is shown to be extremely time-efficient. Known trends with respect to operating conditions are qualitatively captured, and the exhibited behavior is shown to be robust to changes in the rate constants. The feasibility of a chemical degradation mechanism based on peroxide and radical formation is discussed. The proton exchange membrane ͑PEM͒ fuel cell has long been recognized as an important component of the future hydrogen economy. Although significant progress has been made on issues related to performance, the commercial viability of the PEM fuel cell is largely dependent upon overcoming a host of durability and degradation issues; 1 these include poisoning of the anode by carbon monoxide and hydrogen sulfide, 2-6 platinum sintering and dissolution, 7,8 degradation of carbon supports, 9,10 and membrane failure.11,12 Indeed, the lifetime of the PEM fuel cell is highly dependent on the lifetime of the ion-exchange membrane. The majority of membranes used in PEM fuel cells have a perfluorinated backbone and are modified to include sulfonic groups that facilitate the transport of protons. Typical examples of such materials are Aciplex, Flemion, Dow, and DuPont's Nafion, shown in Fig. 1.There are several known failure modes for these perfluorosulfonic acid ͑PFSA͒ membranes during fuel cell operation, involving mechanical, thermal, and electrochemical processes. Mechanical failure can occur in many forms, including tears, cracks, punctures, pinholes, and inadequate sealing, which can lead to reactant crossover and unwanted reactions. Among the causes of mechanical failure are manufacturing imperfections, 13 The most cited cause of membrane failure is chemical degradation, although in reality failure is likely to be a combination of both mechanical and chemical phenomena, the interplay between which is not fully understood. The two paramount steps in the sequence that leads to chemical degradation are ͑i͒ formation of the attacking species and ͑ii͒ attack by the species on the membrane structure. Both remain the subject of much debate. There is, however, a consensus that the chemical degradation of PFSA membranes is initiated by free radical attack on reactive end groups.11,12 Carboxylic acid ͑or other H-containing͒ end groups can form during polymerization or as a result of chemi...

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Current status of ab initio quantum chemistry study for oxygen electroreduction on fuel cell catalysts

Cited by 143 publications

References 61 publications

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

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

Joint density functional theory of the electrode-electrolyte interface: Application to fixed electrode potentials, interfacial capacitances, and potentials of zero charge

Modeling and Simulation of the Degradation of Perfluorinated Ion-Exchange Membranes in PEM Fuel Cells

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