Application of the high-temperature Kelvin probe for in situ monitoring of the charge transfer at the oxygen/zirconia interface. Oxygen chemisorption isobar

Yamawaki, Michio; Бак, Т.; Nowotny, M. K.; Nowotny, Janusz; Sorrell, Charles C.

doi:10.1016/j.jpcs.2004.07.016

Cited by 15 publications

(36 citation statements)

References 7 publications

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“…It is well known that the work function controls the nature of surface oxygen speciation. Two main scenarios related to dioxygen chemisorption include singly ionized molecular (O 2 -) and atomic (O -) species as revealed elsewhere [18]. Nonetheless, at this stage the established quantitative work function-combustion temperature relationship can be used as a guidelining principle for the optimization of the catalyst for soot combustion, and searching for new promising washcoats of DPF filters.…”

Section: Resultsmentioning

confidence: 98%

Role of Electronic Factor in Soot Oxidation Process Over Tunnelled and Layered Potassium Iron Oxide Catalysts

et al. 2013

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This paper describes the investigations of the catalytic activity in soot oxidation over well-defined iron oxide based materials. The nanostructuration of iron oxide by potassium into tunnelled (KFeO 2 ) and layered (K 2 Fe 22 O 34 ) ferrites and the surface promotion with CeO 2 results in the marked increase in the catalytic activity (decrease of the ignition temperature down to 210°C and T 10 % to 310°C). The measurements of the catalysts work function showed that both nanostructuration and surface promotion with ceria of the best KFeO 2 phase led to increase of the electron availability (decrease of the work function). Strong correlation of the catalytic activity in soot combustion of the Ce-K-Fe-O systems with the work function value was revealed for the first time in the model studies, and can be used as a guideline for optimisation of the real catalytic filters.

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Section: Resultsmentioning

confidence: 98%

Role of Electronic Factor in Soot Oxidation Process Over Tunnelled and Layered Potassium Iron Oxide Catalysts

et al. 2013

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“…Studies using work function measurements have shown that the gas-solid equilibrium for the oxygen-YSZ system may be reached at 1173 K. 30,31 In this case the work function changes during oxidation and reduction are well reproducible and the work function remains stable over a prolonged period of time (Fig. 5).…”

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confidence: 92%

“…30,31 (2) Oxidation of YSZ leads to rapid oxygen incorporation into the lattice. (3) Oxidation of YSZ does not lead to the formation of chemisorbed oxygen species.…”

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confidence: 99%

Segregation in zirconia: equilibrium versus non‐equilibrium segregation

Nowotny

Sorrell

Бак

2005

Surface & Interface Analysis

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The present work considers the differences between the following two phenomena: equilibrium segregation, which is a thermodynamic phenomenon where the driving force is excess interfacial energy; and non-equilibrium segregation, which can be produced by phenomenological shocks applied to the solid surface. Fully stabilized cubic yttria-stabilized zirconia (YSZ) is used as the exemplar for these considerations. Equilibrium segregation in YSZ results in enrichment of the surface and near-surface layers in constituent elements, typically yttria and impurities. This segregation is an intrinsic material property and has an impact on the performance of zirconia at elevated temperatures. On the other hand, non-equilibrium segregation leads to a complex distribution of properties (structure and concentration gradients) that are determined by the experimental procedures used rather than being a material property. However, such non-equilibrium segregation can result in localized structural changes. The present paper also considers the effect of the gas phase on surface properties of metal oxides, including YSZ, and the surface dynamics of YSZ at temperatures below that required to reach equilibrium.

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“…Using a high temperature Kelvin probe, M. Yamawaki et al have observed that a 10 mol % yttria doped bulk YSZ sample without an electronic conductor attached to the reaction site, is oxidized in the presence of O 2 at temperatures ranging from 500 to 900 °C. 7 Also observed by M. Yamawaki et al was an ~60 % increase in O -surface coverage upon an increase in temperature from 500 to 700 °C after which a decrease in O -surface coverage was observed as the temperature was increased above 700 °C. Additional evidence of this reduction in response to NO 2 has also been observed for potentiometric electrochemical sensors which use YSZ as a solid electrolyte where the greatest potential is observed at 700 °C.…”

Section: Resultsmentioning

confidence: 83%

Feasibility of a Stack Integrated SOFC Optical Chemical Sensor

Carpenter¹

2007

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The DOE-NETL Innovative Concepts (IC) phase II program investigated the feasibility of harsh environment compatible chemical sensors based on monitoring the surface plasmon resonance (SPR) bands of metal nanoparticle doped YSZ nano-cermets, as a function of fuel concentrations, impurities e.g. CO and temperature(500-900°C). In particular, Au nanoparticles (AuNPs) exhibit a strong surface plasmon resonance (SPR) band whose shape and spectral position is not only highly dependent on the refractive index of the host medium but also on chemical reactions at the interface between the metal and the surrounding environment.Studies have been completed on the oxygen and temperature dependence of the SPR band of the AuNPs, CO sensing studies, oxygen/hydrogen titration experiments, ethanol sensing studies and finally NO 2 sensing studies. Reversible changes in the SPR band are observed for all chemical exposure studies with the sensing mechanism being determined by the oxidative or reductive properties of the exposure gases. Reactions which remove charge from the AuNPs was observed to cause a redshift in the SPR band, while charge donation to the AuNPs causes a blue shift in the SPR band. CO, hydrogen and ethanol in air mixtures were all reductive in nature as they reacted with the YSZ bound oxygen anions forming CO 2 or H 2 O thus ultimately inducing charge donation to the AuNPs and a blue shift in the SPR band. While NO 2 and oxygen were oxidative and induced the production of YSZ bound oxygen anions, charge removal from the AuNPs and a redshift in the SPR band.iii DOE NETL Final Report DE-FG26-04NT42184

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Application of the high-temperature Kelvin probe for in situ monitoring of the charge transfer at the oxygen/zirconia interface. Oxygen chemisorption isobar

Cited by 15 publications

References 7 publications

Role of Electronic Factor in Soot Oxidation Process Over Tunnelled and Layered Potassium Iron Oxide Catalysts

Role of Electronic Factor in Soot Oxidation Process Over Tunnelled and Layered Potassium Iron Oxide Catalysts

Segregation in zirconia: equilibrium versus non‐equilibrium segregation

Feasibility of a Stack Integrated SOFC Optical Chemical Sensor

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