Highly selective and efficient room temperature NO 2 gas sensors based on Zn-doped CuO nanostructure-rGO hybrid
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Highly selective and efficient room temperature NO2 gas sensors based on Zn-doped CuO nanostructure-rGO hybrid Jyoti1 · A. K. Srivastava2 · G. D. Varma1 Received: 24 January 2018 / Accepted: 17 April 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract In the present work nanostructures of Zn-doped CuO with nominal compositions Cu1−xZnxO (x = 0, 0.03, 0.05, 0.07, 0.10, 0.15) have been synthesized via wet chemical method. The field-emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) results show the formation of 1-D nanochain type morphology in pristine CuO and the same is retained up to Zn doping of 7% (x = 0.07). However, for higher Zn doping (x > 0.07) microflower type morphology is observed. The thin films of the as-synthesized pristine and Zn-doped CuO-reduced graphene oxide (rGO) hybrid materials have been fabricated by drop casting method on glass substrates to study their electrical and gas sensing behavior. The temperature dependent resistance measurements confirm semiconducting behavior of the hybrid films. The gas sensing performances of all hybrid films for NO2 gas have been systematically investigated. The results demonstrate that Zn doping in CuO remarkably increases the gas sensing response as compared to pristine CuO. For example, 5% Zn-doped CuO-rGO hybrid sensor shows percentage response of ~ 54.5, whereas pristine CuO-rGO hybrid sensor shows percentage response of ~ 19.6. Furthermore, sensing performance of hybrid films initially increases with increasing x up to x = 0.07 and after this it starts decreasing with x. The measurements of sensing response for x = 0.05 in the temperature range 296–343 K for 40 ppm NO2 exhibit maximum response at room temperature (296 K) and the lowest detection limit of ~ 6 ppm NO2. Moreover, the hybrid sensors exhibit almost negligible response to other gases like CO, N H3, H2S and C l2 at room temperature, indicating their excellent selectivity towards N O2 gas. The detail correlations between the microstructural characteristics of Zn doped CuO nanostructures and gas sensing behavior of the corresponding hybrid films have been discussed and described in this paper.
1 Introduction Noxious, pestilential and eruptive gases are widely produced from agricultural activities, transportation, industries etc. Therefore, for environmental security, monitoring of toxic gases is of paramount importance to modern society. NO2 is one of the most deleterious gas affecting environment as well as living beings. It is mainly liberated from automobiles and combustion of fossil fuels which results in acid rain and the formation of ozone [1, 2]. Therefore, it is pertinent to fabricate highly selective, cheap and efficient room temperature NO2 gas sensing device with excellent stability. * G. D. Varma [email protected] 1
Department of Physics, Indian Institute of Technology, Roorkee 247667, India
Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, I
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