Metal–organic framework-reduced graphene oxide (Zn-BDC@rGO) composite for selective discrimination among ammonia, carbon monoxide, and sulfur dioxide

Abstract

The structural diversity and high surface reactivity of the metal–organic frameworks (MOFs) offer an ideal material platform for various applications such as gas storage, gas separation, catalyst, etc. However, their use in chemiresistive gas sensing is limited due to the requirement of optimized gas adsorption properties with electrical conductivity. In the present investigation, we have modulated the electrical properties of zinc benzene dicarboxylate (Zn-BDC) MOF by modifying it with partially reduced graphene oxide (rGO). The Zn-BDC and rGO composite (Zn-BDC@rGO) was synthesized by utilizing a solvothermal method and multiparametrically tested by various techniques such as X-Ray diffraction (XRD), UV–visible spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and I–V characteristics, for its structural, spectroscopic, morphological, surface area analysis, thermal stability, and electrical characterization, respectively. The synthesized Zn-BDC@rGO composite was deposited via drop casting method on the copper electrodes on a glass substrate (100 µm gap) using the shadow mask technique by the e-beam evaporator, and tested for the detection of ammonia, carbon monoxide, and sulfur dioxide using chemiresistive modality. The principal component analysis (PCA) indicates that the developed sensor selectively discriminates among the NH3, CO, and SO2 gases with low response/recovery time, i.e., 60/120 s at 20 ppm, which is far below the permissible exposure limit (PEL) suggested by The Occupational Safety and Health Administration (OSHA), USA for CO and NH3 and very close to the PEL level of SO2.