Co/Au bimetal synergistically modified SnO2-In2O3 nanocomposite for efficient CO sensing

For improving the sensitivity and selectivity of metal oxide semiconductor (MOS) materials to CO, Co/Au bimetal modified SnO2-In2O3 nanocomposite was prepared to fabricate MOS gas sensors and tested the gas-sensing performance. The results showed that 1 mol%Au decorated 3 mol%Co-doped SnO2-In2O3 nan...

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Bibliographic Details
Published in:	Ceramics international 2023-05, Vol.49 (10), p.15979-15989
Main Authors:	Meng, Fan-Jian, Guo, Xing-Min
Format:	Article
Language:	eng
Subjects:	CO sensing performance Co/Au bimetal modified Fermi levels tuning Schottky barrier SnO2-In2O3 nanocomposite Spill-over catalytic effect
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Summary:	For improving the sensitivity and selectivity of metal oxide semiconductor (MOS) materials to CO, Co/Au bimetal modified SnO2-In2O3 nanocomposite was prepared to fabricate MOS gas sensors and tested the gas-sensing performance. The results showed that 1 mol%Au decorated 3 mol%Co-doped SnO2-In2O3 nanocomposite (1Au-40ISC0.03O, the mole ratio of Sn0.97Co0.03O2 to In2O3 is 3:1) exhibited the response of 14.01 towards 1000ppm CO at 400 °C, which was about 7.5 and 2.3 times higher than that of pristine SnO2 and 40ISO (the mole ratio of SnO2 to In2O3 is 3:1), respectively. Besides, it showed a rapid response time of 4s and good selectivity towards CO against H2, which was about 12 times higher than that of SnO2. Furthermore, the gas sensing enhancement mechanism was revealed based on the results of XPS, UPS and UV–Vis DRS tests. It was found that the oxygen vacancy content was increased by Co doping modification, bringing about the higher baseline resistance and adsorbed oxygen content. Simultaneously, the Fermi level position of Sn0.97Co0.03O2 (SC0.03O) shifted towards the valence band by 1.08eV, resulting in the increase of potential barrier at the interface between SC0.03O and In2O3. After Au decorating, the Schottky barrier also increased due to the different work function values among Au, SC0.03O and In2O3, which were 4.8, 4.68 and 4.17eV, respectively. It facilitated the oxygen adsorption on SC0.03O and Au, improving the material sensitization. Additionally, electron exchange was greatly improved via the spill-over catalytic effect of Au, accelerating the reaction between oxygen ions and CO, and shortening the response time.
ISSN:	0272-8842 1873-3956