An Electrochemically-Driven Reconstruction Strategy to Realize Highly Crystalline Covalent Organic Frameworks for Enhanced Hydrogen Evolution Reaction.

Developing diverse methods to approach highly crystalline covalent organic frameworks (COFs) for improvement of their electrocatalytic hydrogen evolution reaction (HER) activity is important but very challenging. Herein, for the first time, an electrochemically-driven reconstruction strategy is demonstrated to convert semi-polymerized low-crystalline COFs into highly crystalline, structurally ordered COFs with enhanced HER activity. In situ and ex situ characterizations reveal that cyclic voltammetry (CV) cycles can promote crystallinity, thereby leading to improved conductivity, increased active site density, and superior stability. As a result, the highly crystalline COF achieves low overpotentials of 103.6 and 219.4 mV at 10 and 50 mA cm, respectively, with excellent stability (1200 h at 50 mA cm). More importantly, this strategy is generalizable and effective for various imine-linked COFs with different bonding types, significantly improving their crystallinity and HER activity. This work not only establishes a novel method for constructing highly crystalline COFs but also demonstrates the versatility of electrochemically driven structural modulation in enhancing the catalytic performance of COFs.