Tetraphenylethylene and porphyrin-based covalent organic framework with square lattice for effective photocatalytic hydrogen evolution

A crystalline, bi-photoelectric structural unit 2D periodic square lattice covalent organic framework was designed and target synthesized by the Schiff base condensation between 1,1,2,2-tetra(4-formyl-(1,1′-biphenyl)) ethene and 5,10,15,20-tetrakis(4-amino phenyl)-21H,23H-porphyrin with AA stacking structures, named as TP-COF. The TP-COF exhibited good photoelectric response combined with good crystallinity and high specific surface area (1812 m2 g−1). TP-COF with an optical bandgap of 1.80 eV can be used as a visible light responsive photocatalyst, and the speed of hydrogen evolution by TP-COF could achieve up to 58.4 μmol g−1h−1 under visible light irradiation. The efficient photocatalysis performance could be attributed to the photogenerated charge separation and transport of TP-COF by the fluorescence resonance energy transfer (FRET) from tetraphenylethylene to porphyrin. The successful preparation of this type of COF according to the designed structure provides a new way to realize photocatalyst targeting synthesis for better photocatalysis.