Applicability of gas-phase isotope exchange method for investigation of porous materials

Поротникова, Н. М.; Ananyev, M.V.

doi:10.1007/s10008-020-04896-5

Cited by 3 publications

(2 citation statements)

References 51 publications

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“…13,14 Thus, the GPE method was proposed by Ananyev et al to characterize the k tr of porous MIECs using La 0.6 Sr 0.4 MnO 3Àd as an example. 48 The GPE measurement is summarized as follows: (1) changing the oxygen atmosphere by introducing isotopic oxygen ( 18 O 2 ) to the atmosphere with natural oxygen ( 16 O 2 ) after the sample is in equilibrium with natural oxygen at the test temperature. (2) Recording the changes in gas phase 16 O 2 , 16 O 18 O, and 18 O 2 concentrations versus time.…”

Section: Oxygen Isotopic Exchangementioning

confidence: 99%

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

Han

Jiang

Zhang

et al. 2023

Phys. Chem. Chem. Phys.

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Section: Oxygen Isotopic Exchangementioning

confidence: 99%

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

Han

Jiang

Zhang

et al. 2023

Phys. Chem. Chem. Phys.

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“…Because the composite effect has already been detected, we want to investigate the effect of the triple-phase boundary (TPB) in porous materials on the exchange kinetics. A unique in situ isotope exchange gas-phase equilibration (IE-GPE) method based on isotope 16 O/ 18 O equilibration in the gas phase allows to obtain the intrinsic values of heterogeneous exchange rates and oxygen diffusion. , It is also possible to obtain important information about the oxygen diffusion coefficient, namely, if the diffusion coefficient in the volume does not limit the process, and the diffusion along the grain boundaries is insignificant, then the values are comparable, obtained by the SIMS and IE GPE methods. It has been shown on lanthanum–strontium cobaltites, but for lanthanum–strontium manganites there are discrepancies in values, connected with the essential difference of diffusion coefficients in volume and on grain boundaries of materials .…”

Section: Introductionmentioning

confidence: 99%

Interaction of O₂ with LSM–YSZ Composite Materials and Oxygen Spillover Effect

et al. 2021

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The interaction between gas-phase oxygen and LSM−YSZ (LSM is La 0.6 Sr 0.4 MnO 3±δ ; YSZ is ZrO 2 •Y 2 O 3 electrolyte) composite catalytic materials was studied by the in situ method based on isotope equilibration with the gas phase at T = 600−850 °C and pO 2 = 0.2−1.3 kPa. We made an attempt to develop mathematical criteria to prove the appearance of the spillover effect [migration of adsorbed particles from the active phase to triple-phase boundary (TPB)] from the experimental data. The heterogeneous exchange rate (r H ) and the three exchange types (r 0 , r 1 , r 2 ) were calculated, where 0, 1, and 2 differ in the number of surface oxide atoms participating during one elementary exchange act. The heterogeneous exchange rate for lanthanum−strontium manganite was 2.5−3 orders higher than the heterogeneous exchange rate for the zirconia-yttria electrolyte over the investigated temperature range. The exchange mechanism of composites LSM−YSZ was different from the LSM and YSZ oxides due to the fact that the ratios between the rates of the three exchange types of composites were also different from the individual phases. An original model was proposed for describing the kinetic dependences taking into account the oxygen exchange at LSM and YSZ individual oxides, at a TPB, and exchange between oxygen forms in an adsorption layer and at a TPB. It was shown, that at 600 °C, the exchange occurred without a significant effect of the exchange on TPB (r TPB ). The exchange on TPB became considerable with increasing temperature, so that at a temperature of 800 °C and higher, the rate-determining stage was the exchange between the forms of oxygen in the adsorption layer and on TPB, corresponding to the spillover effect. The phenomenon of the oxygen spillover effect on LSM−YSZ composites has been considered.

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Reduced Surface Area for the Oxygen Reduction Reaction in Porous Electrode via Electrical Conductivity Relaxation

Han,

Guo,

Zhang

et al. 2024

Chemistry A European J

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Oxygen reduction reaction (ORR) performance of porous electrode is critical for solid oxide fuel cells (SOFCs). However, the effects of gas diffusion on the ORR in porous media need further investigation, although some issues, such as nonthermal surface oxygen exchange, have been attributed to gas diffusion. Herein, La0.6Sr0.4Co0.2Fe0.8O3‐δ (LSCF) with various porosity, pore radii and gas permeability were investigated via the electrical conductivity relaxation method and analysed using the distributed of characteristic time (DCT) model. The ORR is revealed with three characteristic times, which are gas diffusion, oxygen exchange via the surface corresponding to small pores, and oxygen exchange to large pores. Gas diffusion delays the oxygen surface exchange reaction, resulting in very low chemical oxygen surface exchange coefficient compared with that obtained with dense sample under the assumption that all the surfaces are active for the ORR. Reduced surface area is thus defined to quantitatively represent the gas diffusion effects. The reduced surface area increases with increasing gas permeability, demonstrating the importance of electrode engineering for fast gas transport. Moreover, reduced surface area is suggested for replacing the specific surface area to calculate the electrode polarization resistance using the ALS model.

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Applicability of gas-phase isotope exchange method for investigation of porous materials

Cited by 3 publications

References 51 publications

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

Interaction of O₂ with LSM–YSZ Composite Materials and Oxygen Spillover Effect

Reduced Surface Area for the Oxygen Reduction Reaction in Porous Electrode via Electrical Conductivity Relaxation

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Applicability of gas-phase isotope exchange method for investigation of porous materials

Cited by 3 publications

References 51 publications

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

Interaction of O2 with LSM–YSZ Composite Materials and Oxygen Spillover Effect

Reduced Surface Area for the Oxygen Reduction Reaction in Porous Electrode via Electrical Conductivity Relaxation

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Interaction of O₂ with LSM–YSZ Composite Materials and Oxygen Spillover Effect