Porphyrin-containing Polyimide with Enhanced Light Absorption and Photocatalysis Activity.

A series of porphyrin-containing polyimide (PI) photocatalysts were synthesized by a one-step solvothermal method. Characterization results revealed that porphyrin was uniformly coupled into the PI framework through covalent bonding and the visible-light absorption was greatly improved. The photodegradation activity of porphyrin-containing PIs for methyl orange (MO) under visible light was enhanced significantly, with the highest pseudo-first-order rate constant 35 times higher than that of neat porphyrin and 10 times higher than that of porphyrin-free PI. The enhancement is mainly attributed to an increased light harvesting accompanied by a varied HOMO level, which was clarified by control experiments, characterizations and theoretical calculations. This work provides an insight into multiple effects of dye molecules in dye-containing heterogeneous photocatalysts.