Enhanced CO₂ Detection Using Potentiometric Sensors Based on PIM-1/DBU Imidazolate Membranes

Abstract

A novel potentiometric sensor for carbon dioxide (CO₂) detection utilizing a composite membrane of Polymer of Intrinsic Microporosity (PIM-1) and 18-diazabicyclo[5.4.0]undec-7-ene imidazolate (DBU-imidazolate) is presented. The high surface area and gas permeability of PIM-1, combined with the chemical affinity and ion-exchange properties of DBU-imidazolate, contribute to enhanced CO₂ sensitivity and selectivity. The research objectives included the synthesis of PIM-1 and DBU-imidazolate, the preparation of composite membranes, and the evaluation of their performance as CO₂ sensors. Solvent casting and impregnation methods are employed to prepare the membranes, which are characterized using Thermal Gravimetric Analysis (TGA), and Field Emission Scanning Electron Microscopy (FESEM). CO₂ absorption tests and Electrochemical Impedance Spectroscopy (EIS) are conducted to assess the sensors' performance. The PIM-1/DBU-imidazolate membrane exhibited high efficiency in CO₂ capture and release. Open circuit voltage (OCV) measurements are performed under varying concentrations of CO₂ exposure and cycles of adsorption/desorption. Results show that the membrane achieves steady state faster at higher CO₂ concentrations, with a logarithmic relationship between CO₂ concentration and voltage variation, indicating potential for CO₂ detection in human environments. These results confirm the sensor's ability to detect varying CO₂ concentrations, highlighting its potential for reliable and efficient CO₂ monitoring in environmental and industrial applications.