Supercritical CO2-assisted rapid synthesis of covalent organic framework-based electrocatalyst for efficient two-electron oxygen reduction reaction.

Abstract

Covalent organic frameworks (COFs) hold significant promise as electrocatalysts, but their synthesis is typically constrained by prolonged reaction times (>72 h), high temperatures ( >120 °C), and the use of organic solvents. Conventional methods also involve multiple freeze-pump-thaw cycles, complicating scalability. Herein, we report a supercritical carbon dioxide (Sc-CO2)-assisted strategy for the rapid synthesis of COFs, enabling their direct in-situ growth on carbon substrates. This supercritical-solvothermal approach yields COF@CNT composites that exhibit effective electrocatalytic performance towards the two-electron oxygen reduction reaction (2e- ORR). The resulting catalysts achieve a H2O2 production rate of 94 mol gcat-1 h-1 and a Faradaic efficiency exceeding 95% at 800 mA cm-2. By reducing the consumption of organic solvents, shortening reaction durations, and circumventing high temperatures, this method provides a scalable and efficient route for COF synthesis. Overall, the Sc-CO2 strategy provides a promising platform for the rapid development of COF-based electrocatalysts, combining enhanced efficiency, scalability, and environmental compatibility.