Tailoring surface properties with O/N doping in CNT aerogel film to obtain sensitive and selective sensor for volatile organic compounds detection

Abstract

Volatile organic compounds (VOCs), listed as toxins/hazardous air pollutants are harmful to human health, and challenges associated with VOCs detection are selectivity of sensors. An emerging material CNT aerogel can offer selective and sensitive detection capabilities of VOCs. The CNT aerogel sensor has been synthesized using scalable floating catalyst chemical vapor deposition and doped with oxygen/nitrogen via plasma treatment. The oxygen/ nitrogen doping was introduced to simultaneously manage defect creation, functional group generation, enhance surface chemistry to obtain superior analyte molecule detection. The surface and functional characterization confirm that plasma treatment introduces oxygen/nitrogen doping in individual CNT uniformly throughout the film without disturbing the mechanical integrity of standalone CNT aerogel film. The bare, oxygen and nitrogen-doped CNT aerogel sensors can detect the polar compounds acetone, ethanol, methanol, as well as non-polar compound benzene in the concentration range of 2–100 ppm. The nitrogen-doped CNT aerogel sensor showed the highest sensitivity, selectivity, response (~ 5 fold increase in comparison to bare) with a limit of detection of 50 ppb. Hence, the present study showed the existence of a critical trade-off between doping and sensing performance of CNT aerogel, and enabling proper composition in CNT aerogel, a sensor with significant performance can be fabricated.