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Weakly Humidity‐Dependent Proton‐Conducting COF Membranes
Author(s) -
Cao Li,
Wu Hong,
Cao Yu,
Fan Chunyang,
Zhao Rui,
He Xueyi,
Yang Pengfei,
Shi Benbing,
You Xinda,
Jiang Zhongyi
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202005565
Subject(s) - membrane , materials science , conductivity , covalent organic framework , nucleation , humidity , chemical engineering , proton transport , proton , solvent , fabrication , proton exchange membrane fuel cell , aqueous solution , relative humidity , nanotechnology , composite material , organic chemistry , chemistry , porosity , thermodynamics , medicine , biochemistry , physics , alternative medicine , pathology , quantum mechanics , engineering
Abstract State‐of‐the‐art proton exchange membranes (PEMs) often suffer from significantly reduced conductivity under low relative humidity, hampering their efficient application in fuel cells. Covalent organic frameworks (COFs) with pre‐designable and well‐defined structures hold promise to cope with the above challenge. However, fabricating defect‐free, robust COF membranes proves an extremely difficult task due to the poor processability of COF materials. Herein, a bottom‐up approach is developed to synthesize intrinsic proton‐conducting COF (IPC‐COF) nanosheets (NUS‐9) in aqueous solutions via diffusion and solvent co‐mediated modulation, enabling a controlled nucleation and in‐plane‐dominated IPC‐COF growth. These nanosheets allow the facile fabrication of IPC‐COF membranes. IPC‐COF membranes with crystalline, rigid ion nanochannels exhibit a weakly humidity‐dependent conductivity over a wide range of humidity (30–98%), 1–2 orders of magnitude higher than that of benchmark PEMs, and a prominent fuel cell performance of 0.93 W cm −2 at 35% RH and 80 ° C arising from superior water retention and Grotthuss mechanism‐dominated proton conduction.