MOFs/nanofiber-based capacitive gas sensors for the highly selective and sensitive sensing of trace SO2

Metal-organic frameworks (MOFs) have shown excellent potential for use in advanced gas-detection devices. However, the application range and performance of powdered MOFs are limited. Herein, we report a novel method of loading a MOF (UiO-66-NH2) onto a polyacrylonitrile nanofiber membrane (PAN NM) via an in-situ growth mechanism to obtain a capacitive sensor for the detection of trace amounts of SO2 gas. The prepared UiO-66-NH2/PAN-based capacitive gas sensor has excellent sensing performance for SO2 gas (1-125 ppm). To further improve the detection ability of the sensor toward trace SO2, the UiO-66-NH2 framework is modified by 2,3,4-trihydroxybenzaldehyde (THBA) via a post-synthesis modification approach. Analysis of the experimental results and density functional theory calculations reveal that the abundant hydroxyl groups present on THBA improve the SO2 adsorption performance of the material, enabling a low detection limit (0.1 ppm) of the UiO-66-THB/ PAN-based gas sensor. This work demonstrates the feasibility of developing MOFs/nanofiber membranes as gas sensors.