ZnO nanobristles prepared by one-step thermal decomposition of zinc nitrate as ultra-high response ethanol sensor at room temperature
Room temperature detection of volatile organic compounds (VOC) such as ethanol, methanol, acetone, etc has received significant research attention in recent years. In particular, detection of ethanol at ppm level using low-cost technology is highly desirable as prolonged exposure to ethanol vapor above a threshold has been linked with digestive track cancer to those working on ethanol synthesis. Here we report a simple one step method (thermal decomposition of zinc nitrate) to synthesize ZnO multifaceted nanobristles that show excellent sensitivity to ethanol at room temperature. Electron microscopic analysis revealed formation of uniformly distributed flower-budlike structures (size 2–3 m) each encompassing hundreds of multifaceted nanobristles having diameter and lengths ~ 100 nm and ~ 0.5 micron, respectively. X-ray diffraction of these nanostructures revealed crystalline wurtzite phase of ZnO. Thin films of these nanostructures deposited on glass substrates showed excellent sensitivity to ethanol vapour at room temperature exhibiting a response in excess of 500 (higher than all previous reports) at 150 ppm ethanol exposure. The sensor also showed excellent repeatability and good selectivity to ethanol as compared to several other VOCs tested suggesting its use in practical low-cost ethanol sensor.
The authors gratefully acknowledge MHRD, Govt. of India for the generous funding through the Centre of Excellence (CoE) grant under TEQIP-II, April 2013. P.T. acknowledges University Grant Commission for providing fellowship (UGC-JRF) and thanks Mr. Sandip Ruidas of the CoE, NIT Durgapur for various technical assistances.
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