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

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.