The Synthesis and Electrocatalytic Properties of Nonstoichiometric Ruthenate Pyrochlores

Horowitz, H.S.; Longo, J.M.; Horowitz, H. H.; Lewandowski, J. T.

doi:10.1021/bk-1985-0279.ch009

Cited by 32 publications

(44 citation statements)

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“…Therefore, LaMnO 3 is considered to work as a promoter catalyst in the LaZ-LaMn system. We conclusively demonstrated that the mixed oxide system of 0.7LaZ-0.3LaMn exhibited the highest ORR activity (E on = *0.90 V and Eff 4 [ 95%), which was comparable to those of PbRPb x reported by Horowitz et al [4] and a conventional 20 mass% Pt/C catalyst.…”

Section: Characterizations Of Mn-incorporated Lazsupporting

confidence: 78%

“…The substitution of Mn ion for the Ru-site and the selection of Ln ion with a smaller atomic number were found to be effective in improving the ORR activity in both oxide series. Moreover, we recently examined the ORR activities of Ln 2 Ru 2 O 7-d (LnRMn x , Ln = Pr, Nd, Sm, Gd, Dy, Yb, M = Mn) in 0.1 M KOH [8,9], and demonstrated that the Pb-free NdRMn 0.25 exhibited the highest ORR activity (E on = *0.95 V and Eff 4 [ 90%), which was comparable to those of PbRPb x reported by Horowitz et al [4] and a conventional 20 mass% Pt/C catalyst. However, the pyrochlore NdRMn 0.25 still contains the precious metal Ru.…”

Section: Introductionsupporting

confidence: 57%

“…Oxide alternatives have been known to show high ORR activity, but not so many studies on them have been done so far compared with those on other electrocatalysts. Horowitz et al first reported that the pyrochlores Pb 2 Ru 2-x Pb x O 7-d (PR 2-x Pb x ) synthesized by precipitation method acted as an ORR active electrocatalyst in alkaline solution [4]. Zen et al revealed that PR 2-alkaline solution and that the ORR activities depended on the kinds of A-and B-site ions.…”

Section: Introductionmentioning

confidence: 99%

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Electrocatalytic Activity of the Pyrochlores Ln2M2O7−δ (Ln = Lanthanoids) for Oxygen Reduction Reaction

et al. 2009

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Electrocatalytic oxygen reduction reaction (ORR) activities of the pyrochlore oxides Ln 2 Zr 2 O 7-d (LnZ) and Ln 2 Sn 2 O 7-d (LnS) (Ln = La, Pr, Nd, Sm) were examined in 0.1 M KOH solution at 70°C. The onset potential (E on ) of the oxygen reduction current and the efficiency (Eff 4 ) of 4-electron reduction of oxygen were evaluated by semi-steady state voltammetry with a rotating ring-disk electrode. In both LnZ and LnS series, the E on values were *0.85 V versus reversible hydrogen electrode. A relation was found between the E on values and the lattice parameters; i.e. on the whole, the ORR activity became high with an increase in the lattice parameters. When the Ln ion was the same, the LnZ series exhibited higher ORR activities than the LnS series. The pyrochlore LaZ with the highest ORR activity showed a Eff 4 value higher than 85%. Moreover, Mn-incorporation to LaZ led to a mixed-oxide (1-xLaZ-xLaM) of LaZ and the perovskite LaMnO 3 (LaM). However, the E on value apparently sifted to a more positive potential probably due to LaMnO 3 , and the magnitude of the cathodic ORR current increased with an increase in the mixing content up to x = 0.3. The mixed-oxide 0.7LaZ-0.3LaM exhibited the highest ORR activity (E on = *0.90 V and Eff 4 [ 95%), which was comparable to that of a conventional 20 mass% Pt/C catalyst.

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Section: Characterizations Of Mn-incorporated Lazsupporting

confidence: 78%

Section: Introductionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

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Electrocatalytic Activity of the Pyrochlores Ln2M2O7−δ (Ln = Lanthanoids) for Oxygen Reduction Reaction

et al. 2009

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“…have been widely studied due to their technological importance (e.g., electrode materials (1), catalysts (2,3), and components in thick film resistors (4)). They are metals or magnetic semiconductors depending on the A cations.…”

Section: Ruthenium Pyrochlores Amentioning

confidence: 99%

Structural and Electronic Factors Governing the Metallic and Nonmetallic Properties of the PyrochloresA2Ru2O7−

Lee

Seo

Whangbo

1997

Journal of Solid State Chemistry

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“…Moreover, since the preparation of lead ruthenate by solid-state reactions 28,29 has the disadvantage of needing excess lead, due to lead evaporation, and a synthesis temperature close to the lead ruthenate decomposition temperature (T = 1130K) 30 a new chemical route, called direct condensation method (DCM), was used to synthesize lead ruthenate nanocrystalline powders.…”

Section: Figure 78 Xrd Patterns For Powder Mixture (A)mentioning

confidence: 99%

Electro-catalytically Active, High Surface Area Cathodes for Low Temperature SOFCs

Wachsman¹

2006

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This research focused on developing low polarization (area specific resistance, ASR) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). In order to accomplish this we focused on two aspects of cathode development: (1) development of novel materials; and (2) developing the relationships between microstructure and electrochemical performance.The materials investigated ranged from Ag-bismuth oxide composites (which had the lowest reported ASR at the beginning of this contract) to a series of pyrochlore structured ruthenates (Bi 2-x M x Ru 2 O 7 , where M = Sr, Ca, Ag; Pb 2 Ru 2 O 6.5 ; and Y 2-2x Pr 2x Ru 2 O 7 ), to composites of the pyrochchlore ruthenates with bismuth oxide.To understand the role of microstructure on electrochemical performance, we optimized the Ag-bismuth oxide and the ruthenate-bismuth oxide composites in terms of both two-phase composition and particle size/microstructure. We further investigated the role of thickness and current collector on ASR.Finally, we investigated issues of stability and found the materials investigated did not form deleterious phases at the cathode/electrolyte interface. Further, we established the ability through particle size modification to limit microstructural decay, thus, enhancing stability.The resulting

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The Synthesis and Electrocatalytic Properties of Nonstoichiometric Ruthenate Pyrochlores

Cited by 32 publications

References 0 publications

Electrocatalytic Activity of the Pyrochlores Ln2M2O7−δ (Ln = Lanthanoids) for Oxygen Reduction Reaction

Electrocatalytic Activity of the Pyrochlores Ln2M2O7−δ (Ln = Lanthanoids) for Oxygen Reduction Reaction

Structural and Electronic Factors Governing the Metallic and Nonmetallic Properties of the PyrochloresA2Ru2O7−

Electro-catalytically Active, High Surface Area Cathodes for Low Temperature SOFCs

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