Detection of NO 2 Down to One ppb Using Ion-in-Conjugation-Inspired Polymer

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2019-01, Vol.15 (2), p.e1803896
• Main Authors: Zhou, Jin, Cheng, Xue-Feng, Gao, Bi-Jun, Yu, Chuang, He, Jing-Hui, Xu, Qing-Feng, Li, Hua, Li, Na-Jun, Chen, Dong-Yun, Lu, Jian-Mei
• Format: Article
• Language: English
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201803896

Nitrogen dioxide (NO ) emission has severe impact on human health and the ecological environment and effective monitoring of NO requires the detection limit (limit of detection) of several parts-per-billion (ppb). All organic semiconductor-based NO sensors fail to reach such a level. In this work, using an ion-in-conjugation inspired-polymer (poly(3,3'-diaminobenzidine-squarine, noted as PDBS) as the sensory material, NO can be detected as low as 1 ppb, which is the lowest among all reported organic NO sensors. In addition, the sensor has high sensitivity, good reversibility, and long-time stability with a period longer than 120 d. Theoretical calculations reveal that PDBS offers unreacted amine and zwitterionic groups, which can offer both the H-bonding and ion-dipole interaction to NO . The moderate binding energies (≈0.6 eV) offer high sensitivity, selectivity as well as good reversibility. The results demonstrate that the ion-in-conjugation can be employed to greatly improve sensitivity and selectivity in organic gas sensors by inducing both H-bonding and ion-dipole attraction.