Cu–O/N Single Sites Incorporated 2D Covalent Organic Framework Ultrathin Nanobelts for Highly Selective Visible‐Light‐Driven CO2 Reduction to CO

Developing heterogeneous catalysts with identifiable catalytic sites provides opportunities to explore their structure–activity relationship. Covalent organic framework (COF) represents an emerging class of porous materials that have exhibited great potential in various applications. Herein, a single‐site heterogeneous photocatalyst consisting of 2D COF ultrathin nanobelts coordinated with single Cu–O/N sites (defined as Cu–COF) is synthesized and investigated for visible‐light‐driven CO 2 reduction. The relatively weak N and O binding sites from the imine and methoxy groups of the organic linkers result in active Cu–O/N sites for charge transfer and CO 2 reduction. The resultant Cu–COF with 0.2 wt% Cu only serves as a bifunctional photocatalyst for visible‐light‐driven CO 2 reduction in the absence of a photosensitizer with triethanolamine as the sacrificial reagent. A high CO selectivity of 94% is obtained. This study further demonstrates the great potential of COFs in heterogeneous catalysis with the abundant choices of functional groups in the organic linkers.