In-Situ Growth Wo3@Zif-8 Core-Shell Nanorod Arrays for Highly Responsive and Selective No2 Detection

Abstract

In this research, a two-step hydrothermal method was used to fabricate a NO2 sensor based on WO3@ZIF-8 core-shell nanorods grown on ceramic tubes. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), were used to determine the morphologies, nanostructures, and compositions of the materials. The nanocomposites consisting of WO3@ZIF-8 showed significant sensing response (65) towards 50 ppm NO2 at 200 ºC. The WO3@ZIF-8 core-shell nanomaterials demonstrated exceptional selectivity to NO2 against TEA, and possessed good repeatability. Moreover, the distinctive core-shell nanorods structure promote the process of transferring the electrical charge of the carrier and the response to the targeted gas. The outer coating of ZIF-8 microporous material, with small pore window size (0.5~0.7 nm), had a sieving effect on large molecular interference gases. Further, we combined density functional theory (DFT) calculations and molecular dynamics simulations to investigate the reaction mechanism of the sensors.

Keywords: WO3, ZIF-8, Selectivity, NO2, Gas sensing, DFT