Stable Immobilization of Nickel Ions on Covalent Organic Frameworks for Panchromatic Photocatalytic Hydrogen Evolution

Abstract Post‐coordination design on covalent organic frameworks (COFs) is an efficient strategy for elevating the photocatalytic activity of organic moiety. However, the rigid skeletons and densely layered stacking of two‐dimensional (2D) COFs cannot be flexibly adapted for specific conformations of metal complexes, thereby impairing the metal‐COF cooperation. Here, we adopt a solvothermal method to immobilize nickel(II) ions into a 2,2′‐bipyridine‐containing 2D COF, forming a stable coordination motif. Such the complex remarkably enhances the photocatalytic performance, giving an optimized H 2 evolution rate of as high as 51 300 μmol h −1 g −1 , 2.5 times higher than the pristine COF. The evolved hydrogen gas can also be detected upon 700‐nm light irradiation, while its analog synthesized by the traditional coordination method is photo‐catalytically inert. This work provides a strategy for optimizing the metal‐COF coordination system and strengthening a synergy for electronic regulation in photocatalysis.