Abstract
A novel hybrid structure sensor based on cobalt carbonate hydroxide hydrate (CCHH) and reduced graphene oxide (RGO) was designed for room temperature NH3 detection. This hybrid structure consisted of CCHH and RGO (synthesized by a one-step hydrothermal method), in which RGO uniformly dispersed in CCHH, being used as the gas sensing film. The resistivity of the hybrid structure was highly sensitive to the changes on NH3 concentration. CCHH in the hybrid structure was the sensing material and RGO was the conductive channel material. The hybrid structure could improve signal-to-noise ratio (SNR) and the sensitivity by obtaining the optimal mass proportion of RGO, since the proportion of RGO was directly related to sensitivity. The gas sensor with 0.4 wt% RGO showed the highest gas sensing response reach to 9% to 1 ppm NH3. Compared to a conventional gas sensor, the proposed sensor not only showed high gas sensing response at room temperature but also was easy to achieve large-scale production due to the good stability and simple synthesis process.
Highlights
As an irritating odor and highly toxic gas, ammonia is widely found in industrial exhaust emissions, which is gradually threatening the health of humans and animals
This paper proposed a novel hybrid structure sensor based on cobalt carbonate hydroxide hydrate (CCHH) and reduced graphene oxide (RGO), designed for room temperature NH3 detection
Considering the influence of different proportion on the structure and gas sensing properties, CCHH-RGO-0.4 with the optimized gas sensitivity was systematically characterized as a properties, typical one.CCHH-RGO-0.4 with the optimized gas sensitivity was systematically characterized as a typical one. 3a illustrated a Scanning electron microscope (SEM) image of CCHH-RGO-0.4, revealing the 3-dimensional (3D) CCHH
Summary
As an irritating odor and highly toxic gas, ammonia is widely found in industrial exhaust emissions, which is gradually threatening the health of humans and animals. It is very crucial to develop highly sensitivity ammonia sensors and detection equipment. Semiconductor gas sensors, all using metal oxide semiconductors as sensing materials, are widely applied to detect various gases owing to the good repeatability and low cost [1,2,3]. Have adjusted the aspect ratio of In2 O3 nanowires to prepare gas sensors with a great gas sensing properties to NO2 [4]. The SnO2 nanowire had good gas sensing properties for hydrogen [5]. Wagh et al used modified ZnO thick film to prepare a highly sensitivity ammonia sensor [6]. In order to further improve the gas sensing properties, there were two research ideas in the academic circles all Sensors 2019, 19, 615; doi:10.3390/s19030615 www.mdpi.com/journal/sensors
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