Structurally Locked Cobalt-Metalated Covalent Organic Frameworks for Enhanced Photocatalytic CO₂ Reduction

The development of efficient metal-based covalent organic frameworks (COFs) as photocatalysts for photocatalytic CO₂ reduction remains highly desirable. However, traditional metallization strategies are significantly limited by the inefficient charge separation efficiency of these materials. Herein, two types of structurally locked metal-COFs, namely, BTT-Co-COF and BTT-Ni-COF, have been afforded via anchoring the metallic catalytic sites into COFs. This approach enables the COFs to exhibit enhanced structural rigidity and an excellent charge separation efficiency. Moreover, the BTT-Co-COF demonstrates a remarkable CO production rate of 12.2 mmol g_cat^-1 h^-1 with 93% selectivity from CO₂, which surpasses BTT-Ni-COF (5.5 mmol g_cat^-1 h^-1) and BTT-COF (1.1 mmol g_cat^-1 h^-1) in terms of CO production rate. Besides, the mechanism of photocatalytic CO₂ reduction was also investigated through density functional theory calculations. This work offers a strategy to access structurally locked metal-covalent organic frameworks for the highly efficient production of syngas.