Novel chemoresistive CH4 sensor with 10 ppm sensitivity based on multiwalled carbon nanotubes functionalized with SnO2 nanocrystals

Abstract

Chemoresistive sensors based on multiwalled carbon nanotubes (MWCNTs) functionalized with SnO2 nanocrystals (NCs) have great potential for detecting trace gases at low concentrations (single ppm levels) at room temperature, because the SnO2 nanocrystals act as active sites for the chemisorption of gas molecules, and carbon nanotubes (CNTs) act as an excellent current carrying platform, allowing the adsorption of gas on SnO2 to modulate the resistance of the CNTs. However, uniform conjugation of SnO2 NCs with MWCNTs is challenging. An effective atomic layer deposition based approach to functionalize the surface of MWCNTs with SnO2 NCs, resulting in a novel CH4 sensor with 10 ppm sensitivity, is presented in this paper. Scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy, and Raman spectroscopy were implemented to study the morphology, elemental composition, and the crystal quality of SnO2 functionalized MWCNTs. High resolution TEM images showed that the crystal quality of the functionalizing SnO2 NCs was of high quality with clear lattice fringes and the dimension almost three times smaller than shown thus far in literature. A lift-off based photolithography technique comprising bilayer photoresists was optimized to fabricate SnO2 functionalized MWCNTs-based chemoresistor sensor, which at room temperature can reliably sense below 10 ppm of CH4 in air. Such low level gas sensitivity, with significant reversible relative resistance change, is believed to be the direct result of the successful functionalization of the MWCNT surface by SnO2 NCs.

Effects of O2 plasma and UV-O3 assisted surface activation on high sensitivity metal oxide functionalized multiwalled carbon nanotube CH4 sensors

“…We explored the relative resistance change for 10 ppm methane at two different RH levels. 26 While exposing the SnO 2 -MWCNT sensor to 10 ppm of CH 4 in dry air at the higher RH (approximately 70%), a monotonic resistance increment was observed which was similar to the low RH tests where RH was held constant at 5%, as seen in Fig. 8.…”

Simulations of Graphene Nanoribbon Field Effect Transistor for the Detection of Propane and Butane Gases: A First Principles Study

“…However, the concentration of methane (CH 4 ) gas is increasing day by day due to green house effect. Several efforts have been done for the development of CH 4 gas sensors [47][48][49][50][51][52][53][54][55][56][57][58]. The detection of CH 4 with our proposed device for climatic and household applications can be considered as future work.…”

Carbon nanomaterials and their application to electrochemical sensors: a review

“…The films were robust, thin and could be integrated into flexible and transparent electronic applications. The sensor performed well at low concentrations, exhibiting limits of detection of 1 ppm for NO 2 and 7 ppm for NH 3 Finally, Humayun et al, [196] reported the fabrication of chemoresistive sensors based on SnO 2 nanocrystal functionalised MWCNTs for detecting CH 4 gas with 10 ppm limit of detection. The authors stated that the sensors sensitivity even for trace analytes, (single ppm level),coupled with its significant reversible relative resistance change, was directly related to the extent of successful functionalisation of the MWCNT surface by the SnO 2 nanocrystals, as no response was observed for CH 4 by un-functionalised MWCNT based probes.…”