Electrocatalysis and Inductive Effects at the Gas, Pt/Stabilized Zirconia Interface

Schouler, E.J.L.; Kleitz, M.

doi:10.1149/1.2100614

Cited by 133 publications

(76 citation statements)

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“…It was shown earlier that the polarization loss at the electrodes can be reduced by using mixed-conducting ceria electrolytes, 12 or by introducing the mixed-conducting (reduced zirconia or ceria) layer on the conventional zirconia electrolyte surface. 4,5,[13][14][15] There is, however, no report available exclusively on the effect of ionic conductivity of the electrolyte on the electrode polarization behavior, except our work. 16,17 High ionic conductivity of the electrolyte can, of course, lead to reduced ohmic losses.…”

mentioning

confidence: 75%

“…Diffusion of O 2 (gas) in gas phase through porous LSM layer [11] Dissociative adsorption of O 2 to form O ad on LSM: O 2 (gas) r 2 O ad (LSM) [12] Surface diffusion of O ad to TPB: O ad (LSM) r O ad (TPB) [13] Charge transfer at TPB: O ad (TPB) ϩ 2e Ϫ (LSM) r O 2Ϫ (TPB) [14] Ionic transfer of O 2Ϫ from TPB into zirconia electrolyte: O 2Ϫ (TPB) r O 2Ϫ (zirconia) [15] With an additional reaction path, "mixed-conducting path," a charge transfer may occur at the LSM surface after step 12…”

Section: Discussionmentioning

confidence: 99%

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Effect of Ionic Conductivity of Zirconia Electrolytes on the Polarization Behavior of Various Cathodes in Solid Fuel Cells

Uchida

Yoshida

Watanabe

1999

J. Electrochem. Soc.

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The polarization behaviors of porous platinum and La(Sr)MnO 3 (LSM) cathodes coupled with zirconia electrolytes with various ionic conductivities ( ion ) were investigated. The exchange current density, j 0 , on Pt cathode was not influenced by the ion at 900 and 1000ЊC, whereas j 0 increased proportionally to ion at a lower temperature of 800ЊC. However, the j 0 on LSM cathodes increaesd in proportion to the ion in the temperature region between 800 and 1000ЊC. The dispersion of nanometer-sized Pt catalysts on LSM particles greatly enhanced the performance, the magnitude of which depended on the temperature, the ion , and the microstructure of LSM. The observations are well explained kinetically, i.e., the cathode performance is controlled by the transport rate of O 2Ϫ at the interface when the surface reaction rate is sufficiently high. Consequently, the use of high-performance electrodes in combination with the solid electrolyte having high ion is very important for achieving the high performance of solid oxide fuel cells. © 1999 The Electrochemical Society. S0013-4651(98)03-090-0. All rights reserved.Manuscript submitted March 18, 1998; revised manuscript received September 1, 1998.Solid oxide fuel cells (SOFCs) have been intensively investigated since they are expected to yield fairly high energy conversion efficiencies. At present, the operating temperature of SOFC is restricted to temperatures of about 1000ЊC because of insufficient performance of the state-of-the-art electrolyte and electrodes at low temperatures. Lowering the operating temperature to around 800ЊC is desirable to overcome a limited choice of the component materials resistant to mechanical degradation due to thermal heat shock or to physical and chemical degradation due to oxidation/reduction of materials or to solid-phase reaction at an interface between different materials. However, two major obstacles must be solved to operate SOFCs at medium temperatures. The first is to reduce ohmic losses in solid electrolytes. Progress in this direction has been achieved by the development of a very thin film zirconia electrolyte 1-7 or novel solid electrolytes with higher ionic conductivity. [8][9][10][11] Besides the reduction of ohmic losses, it is very important to develop high performance electrodes since the electrode reaction rates at both anode and cathode are affected detrimentally at medium temperature range.We have been conducting a series of studies with the objective of developing high performance SOFC electrodes operating at relatively lower temperatures than those of the present level. Thus, it becomes essential to clarify the factors that control the polarization properties of these electrodes. It was shown earlier that the polarization loss at the electrodes can be reduced by using mixed-conducting ceria electrolytes, 12 or by introducing the mixed-conducting (reduced zirconia or ceria) layer on the conventional zirconia electrolyte surface. 4,5,[13][14][15] There is, however, no report available exclusively on the effect of ionic ...

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mentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Effect of Ionic Conductivity of Zirconia Electrolytes on the Polarization Behavior of Various Cathodes in Solid Fuel Cells

Uchida

Yoshida

Watanabe

1999

J. Electrochem. Soc.

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“…Concordantly, it has been generally assumed that the reaction (1) may take place only at a tri-phase boundary including the gas phase (involving oxygen), zirconia (involving oxygen vacancies) and electronic conductor (providing electrons) ( Fig. 1) [5,6]. Stabilized zirconia is known as an excellent ionic conductor and very poor electronic conductor [16].…”

Section: Postulation Of the Problemmentioning

confidence: 99%

Interactions of oxygen with yttria-stabilized zirconia at room temperature

Бак

Rękas

Nowotny

et al. 2001

Ionics

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Abstract. This paper reports the results of work function and EPR studies of yttria-stabilized zirconia (10Y-ZrO0. The experimental data are considered in terms of the formation of oxygen chemisorbed species and subsequent oxygen incorporation as well as related charge transfer. It is concluded that oxygen chemisorption on 10Y-ZrO 2 at room temperature in its initial stage results in the formation of 02-species. These species are then transformed into O22-, O-species and, finally, are slowly incorporated into the oxide lattice. These processes take place without presence of Pt or any other electrode material.

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“…This may result in a high oxygen partial pressure at the electrode/solid electrolyte interface during oxygen evolution at anodic overpotentials. As discussed by Schouler and Kleitz [28] and Yanagida [5], at such high oxygen partial pressure holes may be injected in the solid electrolyte resulting in a larger effective electrode area. Such an enlargement of the electrodearea during anodic polar&ion will present itself in a faster increase.…”

Section: Steudy Vute Polorisutiotimentioning

confidence: 99%

Electrode polarization at the Au, O2 (g) / yttria stabilized zirconia interface. Part II: electrochemical measurements and analysis

1991

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The impedance of the Au,O,(g)/yttria stabilized zirconia interface has been measured as function of the overpotential, temperature and oxygen partial pressure. At large cathodic overpotentials (vi -0. I V) and large anodic overpotentials (7~ +O. I V) inductive effects are observed in the impedance diagram at low frequencies. Those inductive effects result from a charge transfer mechanism where a stepwise transfer of electrons towards adsorbed oxygen species occurs. A model analysis shows that the inductive effects at cathodic overpotentials appear when the fraction of coverage of one of the intermediates increases with more negative cathodic overpotentials.The steady state current-voltage characteristics can be analyzed with a Butler-Volmer type of equation. The apparent cathodic charge transfer coefficient is close to 01, =0.5 and the apparent anodic charge transfer coefficient varies between I .7 < (Y, -C 2.8. The logarithm of the equilibrium exchange current density ( lo ) shows a positive dependence on the logarithm ofthe oxygen partial pressure with a slope of m = (0.602 0.02). Both the apparent cathodic charge transfer coefficient and the oxygen partial pressure dependence of I,, are in accordance with a reaction model where a competition exists between charge transfer and mass transport of molecular adsorbed oxygen species along the electrode/solid electrolyte interface. The apparent anodic charge transfer coefficients deviate from the model prediction.

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Electrocatalysis and Inductive Effects at the Gas, Pt/Stabilized Zirconia Interface

Cited by 133 publications

References 14 publications

Effect of Ionic Conductivity of Zirconia Electrolytes on the Polarization Behavior of Various Cathodes in Solid Fuel Cells

Effect of Ionic Conductivity of Zirconia Electrolytes on the Polarization Behavior of Various Cathodes in Solid Fuel Cells

Interactions of oxygen with yttria-stabilized zirconia at room temperature

Electrode polarization at the Au, O2 (g) / yttria stabilized zirconia interface. Part II: electrochemical measurements and analysis

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