Green synthesis of olefin-linked covalent organic frameworks for hydrogen fuel cell applications.

Wang, Zhifang; Yang, Yi; Zhao, Zhengfeng; Zhang, Penghui; Zhang, Yushu; Liu, Jinjin; Ma, Shengqian; Cheng, Peng et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

Green synthesis of crystalline porous materials for energy-related applications is of great significance but very challenging. Here, we create a green strategy to fabricate a highly crystalline olefin-linked pyrazine-based covalent organic framework (COF) with high robustness and porosity under solvent-free conditions. The abundant nitrogen sites, high hydrophilicity, and well-defined one-dimensional nanochannels make the resulting COF an ideal platform to confine and stabilize the H<sub>3</sub>PO<sub>4</sub> network in the pores through hydrogen-bonding interactions. The resulting material exhibits low activation energy (E<sub>a</sub>) of 0.06 eV, and ultrahigh proton conductivity across a wide relative humidity (10-90 %) and temperature range (25-80 °C). A realistic proton exchange membrane fuel cell using the olefin-linked COF as the solid electrolyte achieve a maximum power of 135 mW cm<sup>-2</sup> and a current density of 676 mA cm<sup>-2</sup>, which exceeds all reported COF materials.