Sustainable thermionic O- emission from stoichiometric 12CaO7 Al2O3 with nanoporous crystal structure

Jiang Li, Katsuro Hayashi, Masahiro Hirano, Hideo Hosono

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We have examined electric field-assisted thermionic emission of oxygen radical anion (O-) and electron from a stoichiometric 12CaO7 Al 2O3 (C12A7). Lattice framework of C12A7 is composed of subnanometer-sized cages that can accommodate extra- framework species with negative charge, such as O-, O2- ions, and electrons. Absence of oxygen gas supply leads to a steady coemission of O- ion and electron with a ratio of ∼3:7. However, the oxygen gas supply markedly enhances the O- ion emission and suppresses the electron emission, realizing a sustainable and high-purity O- ion emission with a current density up to 11 nA cm-2 at 825°C. The O- ion emission accompanies a weak O2- ion emission, which is smaller by ∼130. TheO2 pressure at the rear side controls the concentrations of O- ion and electron on the emission surface as well as their concentrations in the bulk, and in turn, determines their emission intensities.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume156
Issue number1
DOIs
Publication statusPublished - 2009
Externally publishedYes

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Crystal structure
Ions
Gas supply
Electrons
Oxygen
Thermionic emission
Electron emission
Anions
Reactive Oxygen Species
Current density
Negative ions
Electric fields

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

Cite this

Sustainable thermionic O- emission from stoichiometric 12CaO7 Al2O3 with nanoporous crystal structure. / Li, Jiang; Hayashi, Katsuro; Hirano, Masahiro; Hosono, Hideo.

In: Journal of the Electrochemical Society, Vol. 156, No. 1, 2009.

Research output: Contribution to journalArticle

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abstract = "We have examined electric field-assisted thermionic emission of oxygen radical anion (O-) and electron from a stoichiometric 12CaO7 Al 2O3 (C12A7). Lattice framework of C12A7 is composed of subnanometer-sized cages that can accommodate extra- framework species with negative charge, such as O-, O2- ions, and electrons. Absence of oxygen gas supply leads to a steady coemission of O- ion and electron with a ratio of ∼3:7. However, the oxygen gas supply markedly enhances the O- ion emission and suppresses the electron emission, realizing a sustainable and high-purity O- ion emission with a current density up to 11 nA cm-2 at 825°C. The O- ion emission accompanies a weak O2- ion emission, which is smaller by ∼130. TheO2 pressure at the rear side controls the concentrations of O- ion and electron on the emission surface as well as their concentrations in the bulk, and in turn, determines their emission intensities.",
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