Sub-ppm sulfur dioxide detection using MoS2 modified multi-wall carbon nanotubes at room temperature

Sulfur dioxide (SO2) is highly toxic to environment and has an adverse effect on a living being. In this report, a chemiresistive SO2 gas sensor based on carboxylic-acid functionalized multiwalled carbon nanotubes/molybdenum disulfide nanocomposite sensing film is reported. The receptor film was characterized with various morphological, microstructural, and compositional tools such as transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. The systematic investigation of gas sensing with this film suggests its selectivity towards SO2 gas with an absolute response of 0.22-1.81% in the concentration range of 500ppb-3 ppm. The room temperature operation of the device at a low biasing voltage (i.e., 100 mV) makes the device energy efficient. Response and recovery time of the device were found to be of the order of tens of seconds without applying any external stimuli. A plausible sensing mechanism is proposed based on active sites present in the nanocomposite is also proposed.