Modulating Order–Disorder Structures in Covalent Organic Frameworks for Photocatalytic CO₂ Reduction to Propylene

Covalent organic frameworks (COFs) are porous ordered materials used for photocatalytic CO2 reduction, but the growth process often introduces disordered units, which inevitably create the “ordered-disordered structure” puzzle. Herein, three COFs with different ordered-disordered structures were prepared under varying hydrothermal synthesis conditions. The moderately ordered-disordered structure COF (MC–COF) showed superior performance in converting CO2 to propylene, achieving a yield of 265.8 μmol g–1 under visible light illumination, whereas the disordered structure COF (PC–COF) exhibited the second highest yield (139.9 μmol g–1), and the highly ordered structure COF (HC–COF) showed the lowest yield (56.9 μmol g–1). Moreover, all three COFs exhibited satisfactory CH4 activity with negligible changes regardless of the ordered-disordered structure. Experimental and theoretical studies revealed that appropriately ordered-disordered structures in the COFs can significantly enhance the visible light trapping ability and the photogenerated carrier migration rates. This work addresses the “ordered-disordered structure” challenge and provides a fundamental perspective for the future design of COFs for selective photocatalytic CO2 reduction to propylene.