Enhanced Conductivity in Conjugated Microporous Polymers via Integrating of Carbon Nanotubes for Ultrasensitive NO ₂ Chemiresistive Sensor

Conjugated microporous polymers (CMPs) present high promise for chemiresistive gas sensing owing to their inherent porosities, high surface areas, and tunable semiconducting properties. However, the poor conductivity hinders their widespread application in chemiresistive sensing. In this work, three typical CMPs (PSATA, PSATB, and PSATT) are synthesized and their chemiresistive gas sensing performance is investigated for the first time. To further improve performance, PSATT are modified on the surface of amino-functionalized multi-walled carbon nanotubes (NH₂-MWCNTs) to improve the conductivity. As a result, the obtained material, PSATT-7NC exhibited a high sensitivity of 9766% toward 4 ppm NO₂, which is 2.5 times higher than that of pristine PSATT. It also demonstrated remarkable selectivity and excellent long-term stability. Furthermore, the lowest limit of detection (0.79 ppb) among all polymers-based sensors is achieved at a low operating temperature of 100 °C. This work provides a valuable strategy into the development of a new material platform for advancing high-performance gas sensing applications.