A chemiresistive gas sensor for sensitive detection of SO2 employing Ni-MOF modified -OH-SWNTs and -OH-MWNTs

Sulfur dioxide (SO2) is prominent as hazardous gas owing to its unpropitious effects on the ecosystem. In this report, a flexible SO2 gas sensor is reported by solvothermally synthesized crystalline nickel(II)benzenetricarboxylate metal-organic framework (Ni-MOF) modified with hydroxyl group (-OH) activated single wall carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), respectively. Introduction of -OH-SWNTs and -OH-MWNTs played crucial role in the improvement in electrical and morphological properties of Ni-MOF as well as boosted the sensing ability toward SO2 gas at room temperature. The structural and spectroscopy properties of pristine Ni-MOF, Ni-MOF/-OH-SWNTs and Ni-MOF/-OH-MWNTs were studied by X-Ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), respectively. Atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM) were used for the morphological analysis of synthesized material. The selective response of Ni-MOF/-OH-SWNTs and Ni-MOF/-OH-MWNTs toward SO2, NO2, NH3 and CO analytes (0.5-15 ppm) was withal studied by monitoring the changes in electrical resistance of the material at room temperature. The present study reveals that doping of -OH-SWNTs and -OH-MWNTs into the MOF leads to efficient increment in the sensing characteristics. The composite of Ni-MOF/-OH-SWNTs exhibited better sensing response (10 s) with less recovery time (30 s) for 1 ppm concentration along with considerable sensitivity (0.9784) and selectivity toward SO2 gas.

Automated summary

In this study, a flexible SO2 gas sensor was developed by modifying crystalline nickel(II)benzenetricarboxylate metal-organic framework (Ni-MOF) with activated single wall carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). The introduction of -OH functionalized carbon nanotubes significantly improved the electrical and morphological properties of Ni-MOF, enhancing its sensing ability towards SO2 gas at room temperature. The composite exhibited efficient sensing characteristics with good selectivity and sensitivity towards SO2 gas.