Bipolaronic Motifs Induced Spatially Separated Catalytic Sites for Tunable Syngas Photosynthesis from CO2

Abstract Photocatalytic reduction of CO 2 into syngas is a promising way to tackle the energy and environmental challenges; however, it remains a challenge to achieve reaction decoupling of CO 2 reduction and water splitting. Therefore, efficient production of syngas with a suitable CO/H 2 ratio for Fischer–Tropsch synthesis can hardly be achieved. Herein, bipolaronic motifs including Co(II)‐pyridine N motifs and Co(II)‐imine N motifs are rationally designed into a crystalline imine‐linked 1,10‐phenanthroline‐5,6‐dione‐based covalent organic framework (bp‐Co‐COF) with a triazine core. These featured structures with spatially separated active sites exhibit efficient photocatalytic performance toward CO 2 ‐to‐syngas conversion with a suitable CO/H 2 ratio (1:1−1:3). The bipolaronic motifs enable a highly separated electron–hole state, whereby the Co(II)‐pyridine N motifs tend to be the active sites for CO 2 activation and accelerate the hydrogenation to form *COOH intermediates; whilst, the Co(II)‐imine N motifs increase surface hydrophilicity for H 2 evolution. The photocatalytic reductions of CO 2 and H 2 O thus decouple and proceed via a concerted way on the bipolaronic motifs of bp‐Co‐COF. The optimal bp‐Co‐COF photocatalyst achieves a high syngas evolution rate of 15.8 mmol g −1 h −1 with CO/H 2 ratio of 1:2, outperforming previously reported COF‐based photocatalysts.