<i>In Situ</i> Charge Exfoliated Soluble Covalent Organic Framework Directly Used for Zn–Air Flow Battery

Abstract

Covalent organic frameworks (COFs) are generally obtained as insoluble, cross-linked powders or films, hindering their superior processable properties especially for device implementation. Here, a soluble COF is created with atomically well-organized positive charged centers constrained in the planar direction, exhibiting exceptional solubility through an in situ charge exfoliation pathway. Once dissolved, the obtained true solution retains homogeneity even after standing over a year. Moreover, the as-designed soluble COF contains ordered N-coordinated Fe single atom centers and conjugated structures, providing a small work function (4.84 eV) and superior catalytic performance for oxygen reduction (high half-wave potential of ∼900 mV). The obtained COF true solution can be directly used as a highly efficient Pt-replaced catalyst for zinc-air flow batteries, generating prominent performance and outstanding stability.