Mimicking Overall Photosynthesis by Incorporating Paired Ce(III) Single-Atom Sites Into Covalent Organic Framework

Artificial photosynthesis that mimics overall photosynthesis towards converting CO₂ and H₂O to C₂₊ chemicals still remains a great challenge due to the lack of efficient photocatalysts containing both water oxidation reaction (WOR) and CO₂ reduction reaction (CO₂RR) active sites with good visible-light absorption capability and matched band structure. Herein, we developed a three-dimensional covalent organic framework (3D COF), BPDA-AmCOF-Ce, containing paired Ce(III) single atomic sites and pyrene moieties. The two-fold interpenetrated bcu topology of BPDA-AmCOF-Ce with two neighboring 2,2'-bipyridine moieties of BPDA results in a short distance of 5.63 Å for paired Ce atoms, capable of inducing C-C coupling in CO₂RR. This, together with exposed pyrene moieties-effective in driving 2e^- WOR, good visible light absorption capacity, and matched band structure, enables BPDA-AmCOF-Ce to exhibit excellent overall photosynthesis performance, converting CO₂ and H₂O to CH₃COOH and H₂O₂ at high production rates of 166.67 and 601.42 µmol g_catalyst ^-1 h^-1, respectively, with selectivity upto 94.4% under visible light (λ > 420 nm) illumination. This work not only provides insights into the design and fabrication of efficient artificial photocatalysts to mimic overall photosynthesis but also highlights the significance of combining COFs with single-atom catalysts towards engineering reaction pathways in photocatalysis.