Oxygen-tolerant CO electroreduction over covalent organic frameworks via photoswitching control oxygen passivation strategy.

The direct use of flue gas for the electrochemical CO reduction reaction is desirable but severely limited by the thermodynamically favorable oxygen reduction reaction. Herein, a photonicswitching unit 1,2-Bis(5'-formyl-2'-methylthien-3'-yl)cyclopentene (DAE) is integrated into a cobalt porphyrin-based covalent organic framework for highly efficient CO electrocatalysis under aerobic environment. The DAE moiety in the material can reversibly modulate the O activation capacity and electronic conductivity by the framework ring-closing/opening reactions under UV/Vis irradiation. The DAE-based covalent organic framework with ring-closing type shows a high CO Faradaic efficiency of 90.5% with CO partial current density of -20.1 mA cm at -1.0 V vs. reversible hydrogen electrode by co-feeding CO and 5% O. This work presents an oxygen passivation strategy to realize efficient CO electroreduction performance by co-feeding of CO and O, which would inspire to design electrocatalysts for the practical CO source such as flue gas from power plants or air.