Herein, we investigated the preparation of composites of cobalt or zinc porphyrins with titania and graphene quantum dots for photoelectrochemical degradation of pentachlorophenol (PCP). Electrochemical analysis was conducted using cyclic voltammetry and electrochemical impedance spectroscopy. The degradation of PCP was followed using UV-vis spectroscopy. The composites of metal porphyrins with titania and graphene quantum dots, exhibited excellent photoelectrochemical degradation results in tha