Optimization of gas sensing properties of n -SnO 2 / p - x CuO sensors for homogenous gases and the sensing mechanism
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Optimization of gas sensing properties of n-SnO2/pxCuO sensors for homogenous gases and the sensing mechanism Wen-dong Zhou1, Davoud Dastan3, Xi-tao Yin2, Shuai Nie2, Saisai Wu2, Qi Wang1,2,* Jing Li2,*
, and
1
School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China The Key Laboratory of Chemical Metallurgy Engineering of Liaoning Province, University of Science and Technology Liaoning, Anshan 114051, China 3 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA 2
Received: 21 April 2020
ABSTRACT
Accepted: 31 August 2020
The gas sensing sensitivity and selectivity are optimized by modulating the concentration of p-type and n-type materials in n-SnO2/p-xCuO nanocomposites. With the increase of x value, the sensing performance of the n-SnO2/pxCuO composites changed from n-type to p-type. Compared with pristine SnO2, the gas sensing response of SnO2–xCuO (x \ 2.78) composites are lower; this can be explained by the opposite gas sensing behavior of SnO2 and CuO to CO and H2; CuO in the SnO2–xCuO (x \ 2.78) composites will offset the reduction in the resistance of pristine SnO2. Compared other as-prepared SnO2–xCuO (x = 1.00, 2.33, 2.80, 3.00, 4.00) composites, the n-SnO2/p-2.78CuO composite (x = 2.78 is the critical value for the p–n transformation) shows the optimal sensing sensitivity and selectivity to CO and H2. The possible gas sensing mechanism for the optimization of the gas sensing performance of n-SnO2/p-2.78CuO composite was illustrated based on the results of gas sensing measurement and the results of XRD, TEM, HRTEM, EDS, and XPS characterization. This behavior can be explained by the following reasons, including plenty of p–n heterojunctions formed in the n-SnO2/p-2.78CuO composite, the numerous chemisorbed oxygen on the surface of the composite, and the 6 nm diameter of the nanoparticles.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Carbon monoxide (CO) is a toxic gas that can be fatal if inhaled because it is toxic to human hemoglobic [1, 2] and CO emissions contribute to air pollution
and global warming with the increasing use of fossil fuels [3, 4]. In particular, CO and hydrogen (H2) are commonly used as important materials in chemical production process and they are inflammable gas, but it is difficult to detect CO and H2 because they are
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https://doi.org/10.1007/s10854-020-04387-3
J Mater Sci: Mater Electron
colorless, tasteless, odorless, and homogeneous gases [5]. Hence, a reliable sensor with high sensitivity and selectivity to CO and H2 is demanded to ensure the safety of production, storage, and delivering. The most commonly applied sensors for monitoring explosive and toxic gases are metal oxide sensors due to the advantages of low cost, easy fabrication, good stability, and fast response [6–8]. In the past few years, n-type metal oxide semiconductors (SnO2, WO3, ZnO, Fe2O3,
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