High Response of ZIF-8-Derived ZnO Nanorods to Low-Concentration Ethylene Glycol

Abstract

Ethylene glycol, a common industrial raw material, finds widespread usage in various production and life applications such as antifreeze and chemical synthesis. However, it poses a threat to human health, being both odorless and colorless, which makes its detection difficult. Previous ethylene glycol sensors have had limited success in detecting low concentrations of the substance (response of 400–30 ppm). Hence, there is a need for a highly responsive and selective ethylene glycol sensor. In this study, different hydrothermal temperatures of 160–180 °C were used to prepare the precursor of ZIF-8, and the final ZnO nanorod sample was prepared accordingly. It was tested in the air environment of 20 °C and 10%RH and the product’s response and selectivity to ethylene glycol were systematically studied. The findings indicate that the sensor exhibited exceptional performance, displaying an ultrahigh response of 3264 for 25 ppm of ethylene glycol when operated at a temperature of 180 °C, along with high selectivity. Notably, in this study, the utilization of various zinc sources led to alterations in the crystal plane spacing of the resultant product. The remarkable gas-sensing performance can be attributed to the heightened presence of surface oxygen defects. Specifically, the oxygen vacancy content of the 200-ZIF sample increased by 9.2%, resulting in the corresponding adjustments in the carrier concentration. The results demonstrate that ZnO derived from ZIF-8 outperforms the hydrothermal method in sensing ethylene glycol, thus offering an approach for the precise detection of this compound.