2D Ionic Conducting Copper(I) MOF in Chemiresistive Sensing of NO2

Abstract

Conducting two-dimensional metal–organic frameworks (2D-MOF) has emerged as a promising class of material in the sensing technologies, but often lags behind traditional metal oxides in terms of sensitivity and repeatability. Herein, a conducting Copper(I) ionic 2D-MOF (iMOF-IITI) constructed with 4-(1H-1,2,4-triazol-1-yl)pyridine is reported for the chemiresistive sensing of NO2. The sensor demonstrates an excellent response of 4456% to 100 ppm NO₂, with rapid response and recovery times of 17.9 and 22.3 s, respectively, and a low detection limit of 0.66 ppb. A comprehensive mechanistic study coupled with X-ray photoelectron spectroscopy (XPS), synchrotron Cu K-edge X-ray absorption spectroscopy, and density functional theory reveals that the MOF's high selectivity and sensitivity stem from preferential NO2 adsorption and efficient charge transfer from the copper centers. This study underscores the potential of Copper(I) iMOFs for ultrasensitive, selective chemiresistive sensing and provides a new avenue for the preparation of iMOF-based chemiresistive sensors. © 2025 Wiley-VCH GmbH.