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

Abstract

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.