Comparison of Reaction Energetics for Oxygen Reduction Reactions on Pt(100), Pt(111), Pt/Ni(100), and Pt/Ni(111) Surfaces: A First-Principles Study

Duan, Zhiyao; Wang, Guofeng

doi:10.1021/jp400388v

Cited by 174 publications

(145 citation statements)

References 45 publications

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“…Over the years these intriguing questions have been examined by density-functional theory (DFT) studies [9][10][11][12][13][14][15][16][17] . The usual model concerns the description of some of the elementary steps of ORR on extended platinum surfaces: molecular oxygen dissociation [18][19][20][21] ; water formation through O+H route 22 ; disproprotionation routes 23,24 ; water formation through OOH pathway 25 .…”

Section: Introductionmentioning

confidence: 99%

Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

Morais

Franco

Sautet

et al. 2015

Phys. Chem. Chem. Phys.

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Understanding the selectivity of the oxygen reduction reaction, especially the formation of water versus hydrogen peroxide in fuel cells, is an ongoing challenge in electrochemistry, surface science and catalysis. In this study, we propose a comprehensive thermodynamic analysis of the reaction intermediates for the formation of water on Pt(111). Density functional theory calculations of all the elementary steps linking hydroxyl and hydroperoxyl surface species with water and hydrogen peroxide have been performed at low (1/12 ML, ML = monolayer) and high (1/4 ML) coverages. The reaction energy variation for the two competing elementary events (molecular oxygen dissociation and hydroperoxyl formation) is strongly coverage-dependent. For the direct dissociation, an increase is observed at low coverage with respect to the usual high coverage picture. The stability of the reaction intermediates is investigated from thermodynamic diagrams. At 353 K and a total pressure of 1 atm, water and hydroxyl surface species are expected to compete for adsorption on Pt(111).

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Section: Introductionmentioning

confidence: 99%

Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

Morais

Franco

Sautet

et al. 2015

Phys. Chem. Chem. Phys.

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“…As compared with the reported binding energies of O (ads) in previous literatures [29][30][31][32] , the A/B-and A-site zirconium atoms with the lowest binding energy are respectively defined as the ORR active sites of the (111) surface of monoclinic and cubic phase zirconia, as shown in Table 3 (111) surface of tetragonal phase zirconia is clearly lower than that at the A-site zirconium atom, as shown in Table 3. A computational hydrogen electrode model, which is proposed by Nørskov et al 13 , is employed to calculate the free energy change of the each elementary reaction step of the associative mechanism (Equation 1-5) for ORR on the chosen surface of zirconia.…”

Section: Resultsmentioning

confidence: 89%

Density functional studies of zirconia with different crystal phases for oxygen reduction reaction

et al. 2015

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For understanding the origin of its catalytic activity, the oxygen reduction reaction (ORR) on zirconia with different phases is investigated by first principles method. The free energy diagrams for an associative mechanism are firstly given to identify the rate-determining step for the ORR on the (111) surface of monoclinic, tetragonal and cubic phase zirconia. The calculation results show that the first electron transfer is the rate-determining step for the ORR on monoclinic and cubic phase zirconia, whereas the last electron transfer is the rate-limiting step for the ORR on tetragonal phase zirconia. The delectron partial density of state for the active zirconium atoms is calculated to explore the relationship between the ORR catalytic activity of zirconia with different phases and their electronic properties. The calculated results show that the catalytic activity of zirconia for ORR is strongly dependent on the d-orbital occupation of their active zirconium atoms.

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“…The O 2 adsorption energy varies and depends on a number of factors including surface coverage, adsorption site and phase in contact with Pt (gas, ionomer). [71][72][73] An O 2 adsorption energy range was added to Figure 5. For contaminant adsorption energies >−24.5 kJ mol −1 , O 2 has a smaller adsorption energy and sticks more strongly to the catalyst surface than the contaminant.…”

Section: Resultsmentioning

confidence: 99%

Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

St‐Pierre

Zhai

2016

J. Electrochem. Soc.

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A database summarizing the effects of 21 contaminants on the performance of proton exchange membrane fuel cells (PEMFCs) was used to examine relationships between cathode kinetic losses and contaminant physicochemical parameters. Impedance spectroscopy data were employed to obtain oxygen reduction kinetic resistances by fitting data in the 10−158 Hz range to a simplified equivalent circuit. The contaminant dipole moment and the adsorption energy of the contaminant on a Pt surface were chosen as parameters. Dipole moments did not correlate with dimensionless cathode kinetic resistances. In contrast, adsorption energies were quantitatively and linearly correlated with minimum dimensionless cathode kinetic resistances. Contaminants influence the oxygen reduction for contaminant adsorption energies smaller than −24.5 kJ mol −1 , a value near the high limit of the adsorption energy of O 2 on Pt. Dimensionless cathode kinetic resistances linearly increase with decreasing O 2 adsorption energies below −24.5 kJ mol −1 . Measured total cell voltage losses are mostly larger than the cathode kinetic losses calculated from kinetic resistance changes, which indicates the existence of other sources of performance degradation. Modifications to the experimental procedure are proposed to ensure that data are comparable on a similar basis and improve the correlation between contaminant adsorption energy and kinetic cell voltage PEMFCs are attractive energy conversion devices. However, improvements are still required to meet the strict demands of automotive and other markets. PEMFCs are expected to be durable but are exposed to a variety of contaminants either present in air and hydrogen or released by fuel cell system materials, which may be deleterious to performance. 1-3 Only a small fraction of the large number of likely contaminants have been investigated. For example, only 21 ambient air species from a list of more than 200 candidates were recently studied. 4 Furthermore, fuel cell contamination tests require significant resources and may last several tens or a few hundreds of hours, even if accelerated conditions achieved with higher contaminant concentrations are used. As a result, there is a need to develop a simpler method to predict the impact of contaminants on fuel cell performance.A prediction method for the performance loss associated with contamination has not been suggested for PEMFCs. However, the use of a molecule dipole moment was proposed to correlate the halfwave potential of the oxygen reduction reaction. 5 Only 5 contaminants were considered, and data were obtained with a thin film catalyst layer electrode mounted in a conventional three-electrode cell filled with an aqueous electrolyte maintained at room temperature. These operating conditions are significantly different from the PEMFC environment with a solid electrolyte and the presence of a gas diffusion layer covering the catalyst layer.The PEMFC performance database resulting from separate tests performed with 21 airborne contaminants 4 is reexamined ...

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Comparison of Reaction Energetics for Oxygen Reduction Reactions on Pt(100), Pt(111), Pt/Ni(100), and Pt/Ni(111) Surfaces: A First-Principles Study

Cited by 174 publications

References 45 publications

Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

Density functional studies of zirconia with different crystal phases for oxygen reduction reaction

Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

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