Room temperature trace level detection of NO2 gas using SnO2 modified carbon nanotubes based sensor

A hybrid SnO2 modified multiwalled carbon nanotubes (MWCNTs) gas sensor is developed for the trace level (100 ppb) detection of NO2 gas at room temperature. A simple method is applied for the synthesis of a hybrid sensor; SnO2-modified multiwalled carbon nanotubes (MWCNTs), in which MWCNT bundles are uniformly coated in situ with SnO2 nanoparticles (similar to 4 nm). The concentration of MWCNTs has been varied and the hybrid MWCNT-SnO2 sensor prepared using an optimum content of MWCNT (5 mg) is found to exhibit enhanced sensing response characteristics (response = 5.5 x 10(3)) towards 100 ppb NO2 gas at a low operating temperature of 50 degrees C, with comparatively faster response and recovery speeds of 2.3 min and 6.8 min, respectively, as compared to sensor structure based structures based on thin films of pure SnO2 nanoparticles (response = 1.01 x 10(2)). The hybrid sensor also exhibits a good response (1.07 x 10(3)) to 100 ppb NO2 gas at room temperature. Extensive modulation of the space charge regions formed at the interface of n-type semiconducting nanoparticles of SnO2 with p-type MWCNTs with interaction to the NO2 gas along with providing the conducting channels by CNTs for charge carriers are responsible for the enhanced response characteristics of the hybrid sensor.