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ZnO/RGO Heterojunction based near Room temperature Alcohol Sensor with Improved Efficiency
Sanghamitra Ghosal * 1 , Partha Bhattacharyya 2
1  School of VLSI Technology, Indian Institute of Engineering Science & Technology (IIEST), Howrah 711103, India
2  Nano Thin Film and Solid State Gas Sensor Based Devices Laboratory, Indian Institute of Engineering Science & Technology (IIEST), Howrah 711103, India

Published: 17 May 2021 by MDPI in 8th International Symposium on Sensor Science session Chemical Sensors
10.3390/I3S2021Dresden-10073 (registering DOI)

Systematic optimization of surface engineering (dimensionality) indeed plays a crucial role for achieving efficient vapor sensing performance. Among various semiconducting metal oxides, owing to some of its unique features and advantages, ZnO has attracted worldwide researchers for application in various fields including chemical sensors. Concomitant optimization of the surface attributes (varying different dimensions) of ZnO became a sensation for the entire research family. Moreover, the small thickness and extremely large surface of exfoliated 2D nanosheets render the gas sensing material as an ideal candidate, for achieving strong coupling with different gas molecules. However, temperature is a crucial factor in the field of chemical sensing. Recently, graphene-based gas sensors have attracted attention due to their variety of structures, unique sensing performances and room temperature working conditions. In this work, highly sensitive and fast responsive low temperature (60 ºC) based ethanol sensor, based on RGO/2D ZnO nanosheets hybrid structure, is reported. After detailed characterizations, vapor sensing potentiality of such sensor was tested for the detection of ethanol. The ethanol sensor offered the response magnitude of 89% (100 ppm concentration) with response and recovery time of 12 s/29 s respectively. Due to excessively high number of active sites for VOC interaction, with high yield synthesis process and appreciably high carrier mobility, paved the path for developing future generation, miniaturized and flexible (wearable) vapor sensor devices meeting the multidimensional requirements for traditional and upcoming (health/medical sector) applications. Underlying mechanistic framework for vapor sensing, through such hybrid junction, was explained with the Energy Band Diagram.

Keywords: 2D ZnO nanosheets; hybrid structure of ZnO/RGO; vapor sensing performance; energy band diagram