Reduced graphene oxide (rGO) decorated ZnO-SnO2: A ternary nanocomposite towards improved low concentration VOC sensing performance

Abstract

A ternary p-n-n heterojunction has been prepared by introducing reduced graphene oxide (rGO) in ZnO-SnO2 nanocomposite and its ppm level volatile organic compounds (VOCs) sensing properties have been exploited. Using a simple, facile sol-gel process, initially, ZnO-SnO2 nanocomposites containing different concentrations of ZnO and SnO2 were prepared and subsequently this was followed by rGO incorporation. The as-synthesized powders were well characterized through XRD, FTIR, Raman spectroscopy, FESEM, TEM, and XPS analyses. The sensing study revealed that, the ternary nanocomposite sensor delineated ~91% n-type sensing response towards ~10 ppm acetone gas at an optimum working temperature of 150 °C. Even it could sense ~1 ppm acetone with appreciable sensing response of ~71%. Additionally, the sensor displayed fast response (~10 s) and recovery time (~100 s) suitable for detection of multiple pulses in short time duration. It also exhibited a considerable ~65% sensing response towards ~10 ppm ethanol at 150 °C. These superior sensing performances of rGO decorated ZnO-SnO2 nanocomposite illustrated with band structure modification. Our results indicated that, the fabricated rGO decorated ZnO-SnO2 sensor, with remarkable high sensing response, minimum interference from other toxic, inflammable gases and profound long term stability, could be considered as a prolific candidate for real time detection of low concentration VOCs in versatile commercial applications.