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Nanocomposites SnO2/SiO2 for CO Gas Sensors: Microstructure and Reactivity in the Interaction with the Gas Phase
Open AccessArticle

Nanocomposites SnO2/SiO2:SiO2 Impact on the Active Centers and Conductivity Mechanism

1
Chemistry Department, Moscow State University, Moscow 119991, Russia
2
Faculty of Physics, Moscow State University, Moscow 119991, Russia
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National Research Center Kurchatov Institute, Moscow 123182, Russia
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Department of Nano-, Bio-, Information Technology and Cognitive Science, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141701, Russia
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Boreskov Institute of Catalysis SB RAS, Novosibirsk, 630090 Russia
*
Author to whom correspondence should be addressed.
Materials 2019, 12(21), 3618; https://doi.org/10.3390/ma12213618
Received: 2 October 2019 / Revised: 29 October 2019 / Accepted: 1 November 2019 / Published: 4 November 2019
(This article belongs to the Special Issue Metal Oxide Semiconductors for Gas Sensor Applications)
This paper is focused on the effect of the stabilizing component SiO2 on the type and concentration of active sites in SnO2/SiO2 nanocomposites compared with nanocrystalline SnO2. Previously, we found that SnO2/SiO2 nanocomposites show better sensor characteristics in CO detection (lower detection limit, higher sensor response, and shorter response time) compared to pure SnO2 in humid air conditions. Nanocomposites SnO2/SiO2 synthesized using the hydrothermal method were characterized by low temperature nitrogen adsorption, XRD, energy dispersive X-ray spectroscopy (EDX), thermo-programmed reduction with hydrogen (TPR-H2), IR-, and electron-paramagnetic resonance (EPR)-spectroscopy methods. The electrophysical properties of SnO2 and SnO2/SiO2 nanocomposites were studied depending on the oxygen partial pressure in the temperature range of 200–400 °C. The introduction of SiO2 results in an increase in the concentration of paramagnetic centers Sn3+ and the amount of surface hydroxyl groups and chemisorbed oxygen and leads to a decrease in the negative charge on chemisorbed oxygen species. The temperature dependences of the conductivity of SnO2 and SnO2/SiO2 nanocomposites are linearized in Mott coordinates, which may indicate the contribution of the hopping mechanism with a variable hopping distance over local states. View Full-Text
Keywords: nanocomposites; tin dioxide; silicon dioxide; oxygen chemisorption; active surface groups; paramagnetic centers; conductivity mechanism nanocomposites; tin dioxide; silicon dioxide; oxygen chemisorption; active surface groups; paramagnetic centers; conductivity mechanism
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Gulevich, D.; Rumyantseva, M.; Marikutsa, A.; Shatalova, T.; Konstantinova, E.; Gerasimov, E.; Gaskov, A. Nanocomposites SnO2/SiO2:SiO2 Impact on the Active Centers and Conductivity Mechanism. Materials 2019, 12, 3618.

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