The facile preparation of porphyrin based hierarchical micro/nano assemblies and their visible light photocatalytic activity

Porphyrin nanostructures are widely used in the field of visible light catalysis due to their superior light absorption properties and good controllability in size, shape and function. In this paper, the development of various morphologies in three types of porphyrins with three different phenyl substituents (designated as H2TTP, H2TPP and H2TCPP, respectively) is demonstrated. The formation mechanism proposed was based on the evolution of morphology as functions of molecular structure and solvent mixture. These nano/micro assemblies are well characterized by SEM, IR, UV-vis, X-ray diffraction and photoelectric conversion. The photocatalytic oxidation reactions under visible light irradiation of 1,5-dihydroxynaphthalene (DHN) in water is utilized to evaluate the photoactivity of the as-prepared porphyrin assemblies. The photocatalytic results indicate that the obtained porphyrin assemblies exhibit enhanced visible-light photocatalytic activity. In addition, the photocatalyst is easy to separate and recover, and has good stability. The possible photocatalytic degradation mechanism of DHN by the porphyrins nanopolyhedron photocatalyst was also proposed.