Low level NO2 detection under humid background and associated sensing mechanism for mesoporous SnO2

• Published in: Sensors and actuators. B, Chemical Vol. 231; pp. 166 - 174
• Main Authors: Stanoiu, Adelina, Somacescu, Simona, Calderon-Moreno, Jose Maria, Teodorescu, Valentin Serban, Florea, Ovidiu Gabriel, Sackmann, André, Simion, Cristian Eugen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-2016
• Subjects: Detection; Drying; Electrical resistance and work function changes; Hydroxylation; Mesoporous SnO2; Nitrogen dioxide; Porosity; Sensing mechanism; Sensors; Surface hydroxylation; Tin dioxide; Tin oxides; Surface hydroxylation; Electrical resistance and work function changes; Mesoporous SnO2; Sensing mechanism
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2016.02.137

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Mesoporous SnO2 prepared by a hydrothermal synthesis route assisted by the ionic surfactant Cetyltrimethylammonium bromide, has rutile-type tetragonal symmetry, small homogeneous nanocrystallite size of ∼4nm and good thermal stability. Porosity analysis revealed high surface area ∼127m2/g and a narrow pore size distribution, with an average pore diameter ∼4nm. The mesoporous structure is likewise advantageous towards enhancing the surface reactivity and subsequent gas sensing performances. The role played by the surface hydroxylation on the NO2 sensing mechanism was discussed with respect to the associated photoelectron spectral components. Under humid air, associated with the in-field conditions, the highest sensitivity was attained at 150°C, were the sensor signal towards NO2 is 4 times higher than the one recorded in dry air. This feature has been experimentally demonstrated by simultaneous electrical resistance and work function changes measurements conducted in the range of 400–5000ppb NO2.