Hydrogen Bond Activation by Pyridinic Nitrogen for the High Proton Conductivity of Covalent Triazine Framework Loaded with H3PO4

• Published in: ChemSusChem Vol. 15; no. 23
• Main Authors: Liu, Manying, Deng, Wei‐Hua, Wang, Xueqing, Liu, Jing, Jin, Shangbin, Xu, Gang, Tan, Bien
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 07.12.2022
• Subjects: anhydrous; covalent triazine frameworks; High temperature; Hydrogen bonds; Nitrogen; Proton conduction; proton conduction mechanism; proton-conducting material
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202201298

Under high temperature anhydrous conditions, it is still a formidable challenge to improve the performance of proton‐conducting materials based on H3PO4 and elucidate its proton conduction mechanism. Herein, a highly stable covalent triazine frameworks (CTFs) based on H3PO4 is reported. The more pyridinic nitrogen CTFs contain, the higher proton conductivity is. Compared with H3PO4@CTF−L with less pyridinic nitrogen, H3PO4@CTF−H has a higher proton conductivity of 1.6×10−1 S cm−1 at 150 °C under anhydrous conditions, which does not decay after about 18 months exposure in air. The high proton conductivity is associated with the formation and breaking of the activated Ntriazine⋯H+⋯H2PO4− pairs by pyridinic nitrogen of CTFs. The outstanding long‐term stability is mainly attributed to the ultra‐strong triazine skeleton structure of CTFs. Flow of protons: The proton transport of H3PO4@CTFs relies on the reorganization of activated hydrogen bonds of H3PO4 by the alkaline pyridinic nitrogen under anhydrous conditions. H3PO4@CTFs is a very stable and high‐performance proton exchange membrane material.