Theory of Sensitivity of Nanoscale-Structured Layers of Metal Oxides to Reducing Gases

A theory of sensor response on reducing gases of nanoscale-structured semiconducting oxides with the high concentration of conduction-band electrons has been developed (modeled on In 2 O 3 ). The distribution of charges in nanoparticles is determined by the functional relationship of the density of...

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Bibliographic Details
Published in:Russian journal of physical chemistry. B 2019, Vol.13 (1), p.190-195
Main Authors: Bodneva, V. L., Kozhushner, M. A., Posvyanskii, V. S., Trakhtenberg, L. I.
Format: Article
Language:English
Subjects:
Atomic oxygen
Chemical Physics of Nanomaterials
Chemical reactions
Chemistry
Chemistry and Materials Science
Conduction bands
Conduction electrons
Density
Indium oxides
Nanoparticles
Organic chemistry
Oxygen atoms
Oxygen ions
Physical Chemistry
Sensitivity
Sensors
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Summary:A theory of sensor response on reducing gases of nanoscale-structured semiconducting oxides with the high concentration of conduction-band electrons has been developed (modeled on In 2 O 3 ). The distribution of charges in nanoparticles is determined by the functional relationship of the density of negative and positive charges in nanoparticles and electrons on their surface. The capture of conduction electrons by adsorbed oxygen atoms causes electron redistribution in nanoparticles, such that the near-surface density of electrons and the conductivity of the system decrease. In this case, the conditions of the association and dissociation of oxygen molecules on the surface also change. During the adsorption of reducing gases (H 2 , CO), atomic oxygen ions react with them and electrons are released that enter bulk nanoparticles. The conductivity of the system increases, which corresponds to the sensor effect. A kinetic scheme of chemical reactions, which corresponds to the that described above, has been plotted and corresponding equations were solved. As a result, theoretical dependences of the sensitivity of sensor on the temperature and pressure of hydrogen were found, which agree well with experimental curves at qualitative and quantitative level.
ISSN:1990-7931
1990-7923
DOI:10.1134/S1990793119010068