Confining Phosphoric Acid in Quaternized COF Channels for Ultra‐Stable and Fast Anhydrous Proton Transport
Xiao Pang, Benbing Shi, Yawei Liu, Hong Wu, Jianliang Shen, Jingyuan Guan, Xiaoyao Wang, Chunyang Fan, Zhen Li, Tianhao Zhu, Yan Kong, Zhongyi Jiang
Abstract
Abstract Phosphoric acid (H 3 PO 4 ) doping is a widely employed strategy to facilitate anhydrous proton transport in high‐temperature proton exchange membrane fuel cells (HT‐PEMFCs). However, significant H 3 PO 4 leaching during long‐term operation poses critical challenges to maintaining membrane stability and proton conductivity. Herein, H 3 PO 4 is incorporated into positively charged nanochannels of quaternized covalent organic framework membranes (QACOFMs), leveraging strong electrostatic interactions and confinement effects to achieve exceptional H 3 PO 4 retention under hydration conditions. Moreover, the shortened hydrogen bond length between H 3 PO 4 (O−H…O <2.7 Å) and the highly interconnected hydrogen bond network in the H 3 PO 4 @QACOFMs facilitate ultra‐fast anhydrous proton transport. As a result, the H 3 PO 4 @QACOFMs exhibit superior anhydrous proton transport in a broader temperature range (60 °C–200 °C) and the highest proton conductivity reaches about 379.7 mS cm −1 at 200 °C.