Dual Photosensitizer Coupled Three-Dimensional Metal-Covalent Organic Frameworks for Efficient Photocatalytic Reactions

In this work, we innovatively assembled two types of traditional photosensitizers, that is pyridine ruthenium/ferrum (Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+)) and porphyrin/metalloporphyrin complex (2HPor/ZnPor) by covalent linkage to get a series of dual photosensitizer-based three-dimensional metal-covalent organic frameworks (3D MCOFs), which behaved strong visible light-absorbing ability, efficient electron transfer and suitable band gap for highly efficient photocatalytic hydrogen (H-2) evolution. Rubpy-ZnPor COF achieved the highest H-2 yield (30 338 & mu;mol g(-1) h(-1)) with apparent quantum efficiency (AQE) of 9.68 %@420 nm, which showed one of the best performances among all reported COF based photocatalysts. Furthermore, the in situ produced H-2 was successfully tandem used in the alkyne hydrogenation with & AP;99.9 % conversion efficiency. Theoretical calculations reveal that both the two photosensitizer units in MCOFs can be photoexcited and thus contribute optimal photocatalytic activity. This work develops a general strategy and shows the great potential of using multiple photosensitive materials in the field of photocatalysis.

Automated summary

In this work, dual photosensitizer-based three-dimensional metal-covalent organic frameworks (3D MCOFs) were successfully assembled by covalently linking pyridine ruthenium/ferrum (Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+)) and porphyrin/metalloporphyrin complex (2HPor/ZnPor). These MCOFs demonstrated strong visible light-absorbing ability, efficient electron transfer, and suitable band gap, leading to highly efficient photocatalytic hydrogen (H-2) evolution. The Rubpy-ZnPor COF showed the highest H-2 yield (30,338 μmol g(-1) h(-1)) with an apparent quantum efficiency (AQE) of 9.68% at 420 nm, which is one of the best performances among all reported COF-based photocatalysts. Theoretical calculations revealed that both photosensitizer units in MCOFs can contribute to the optimal photocatalytic activity. This work establishes a general strategy and demonstrates the great potential of utilizing multiple photosensitive materials in the field of photocatalysis.