Enhancement of Lewis Acidity of Cr-Doped Nanocrystalline SnO2: Effect on Surface NH3 Oxidation and Sensory Detection Pattern

Alexey V. Garshev, Vladimir K. Ivanov, Alina A. Krotova, Darya G. Filatova, Elizaveta A. Konstantinova, Daniil O. Naberezhnyi, Nikolay O. Khmelevsky, Artem V. Marikutsa, Pavel A. Kots, Andrey V. Smirnov, Marina N. Rumyantseva, Alexander M. Gaskov, Valeriy V. Krivetskiy

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding ammonia oxidation over metal oxide surfaces is crucial for improving its detection with resistive type gas sensors. Formation of NOx during this process makes sensor response and calibration unstable. Cr-doping of nanocrystalline metal oxides has been reported to suppress NO2 sensitivity and improve response towards NH3, however the exact mechanism of such chromium action remained unknown. Herein, by using EPR spectroscopy we demonstrate formation of Cr(VI) lattice defects on the surface of nanocrystalline Cr-doped SnO2. Enhancement of Cr-doped SnO2 surface acidity and ammonia adsorption as a result has been revealed by using in situ IR spectroscopy. Moreover, a decrease in concentration of free electrons in the conduction band has been shown as a result of substitutional Cr(III) defects formation. Weaker NOx chemisorption during ammonia oxidation over SnO2 surface after Cr doping has been found with the use of mass-spectrometry assisted NH3 thermo-programmed desorption. The given example of surface acidity adjustment and electronic configuration by means of doping may find use in the design of new gas-sensing metal oxide materials.

Original languageEnglish (US)
Pages (from-to)1985-1996
Number of pages12
JournalChemPhysChem
Volume20
Issue number15
DOIs
StatePublished - Aug 5 2019

Keywords

  • ammonia
  • doping
  • metal oxide
  • semiconductors
  • sensors

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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