Rational Crystalline Covalent Organic Frameworks Design for Efficient CO2 Photoreduction with H2O.

Solar energy-driven conversion of CO2 into fuels with H2O as sacrificial agent is still a challenging research field in photosynthesis. Here, a series of crystalline porphyrin-tetrathiafulvalene covalent organic frameworks (COFs) are synthesized and used as photocatalysts for reducing CO2 with H2O, in the absence of additional photosensitizer, sacrificial agent and noble metal co-catalyst. The effective photogenerated electrons transfer from tetrathiafulvalene to porphyrin by covalent bond, resulting in the separated electrons and holes respectively for CO2 reduction and H2O oxidation. By adjusting the band structures of TTCOFs, TTCOF-Zn achieved the highest photocatalytic CO production of 12.33 μmol with ~100 % selectivity, along with H2O oxidation to O2. Furthermore, density function theory calculations combined with the crystal structure model confirmed the structure-function relationship. Our work provides a new sight for designing more efficient artificial crystalline photocatalysts.

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