Influence of metal-porphyrins on the photocatalysis of graphitic carbon nitride

A series of novel metal-porphyrins (MTPPs, M(II) = Co, Ni, Cu) hybridized graphite-like carbon nitride (g-C3N4) has been successfully synthesized by a facile solvothermal method. The microstructure and chemical structure of the MTPP/g-C3N4 nanocomposites were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The MTPP/g-C3N4 nanocomposites exhibited enhanced photocatalytic performances for the photodegradation of rhodamine B in comparision with those of g-C3N4 and the MTPPs precursors. The excellent photocatalytic performance was observed for CoTPP/g-C3N4 compared to those of g-C3N4, NiTPP/g-C3N4 and CuTPP/g-C3N4. The rational mechanisms responsible for deteriorating pollutants were proposed, which could be mainly ascribed to the more effective interfacial charge transfer and the interfacial electronic interactions between CoTPP and g-C3N4. The UV-visible diffused reflectance spectroscopy, photoluminescence, photocurrent spectroscopy and electrochemical impedance spectroscopy studies confirmed that the charge separation efficiency was greatly improved by coupling g-C3N4 with MTPPs.