Covalent Organic Frameworks with Tunable Bridge Positions for Photocatalytic CO2 Reduction to Propylene Under Visible Light Illumination

Abstract

The use of sunlight to convert CO2 into multi‐carbon fuels, particularly propylene, is considered a sustainable carbon cycle pathway, but propylene requires a multi‐electron‐coupled proton reaction process that has not been reported. Herein, two covalent organic frameworks (DA‐COF and DP‐COF) are prepared by varying the bridging positions of anthraquinone conjugated units. The experimental results show that the neighbouring bridge in DA‐COF forms a unique cleavage structure like an enzyme catalyst, which can provide an efficient microenvironment for the reduction reaction to trap protons. At the same time, the neighbor bridging in DA‐COF can form an electron donor‐electron acceptor structure to accelerate the photogenerated carrier migration. As a result, DA‐COF exhibits excellent visible light propylene production with a yield of 270.54 µmol g−1 and no C₃H₆ product is detected by the DP‐COF during the reduction process. This study presents a novel avenue for the production of high value‐added multi‐carbon products using photocatalysis.