Composites of Cobalt and Zinc Porphyrins with Titania and Graphene Quantum Dots for Photoelectrodegradation of Pentachlorophenol

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 that the removal efficiency and catalytic rates were enhanced compared to individual components. Among the tested systems, zinc porphyrin-TiO2-GQDs exhibited the highest removal efficiency up to (80.5%) and catalytic rate of (1.7 × 10− 2) in the absence of H2O2. When H2O2 was added, a significantly improved PCP degradation with up to 94.0% removal efficiency and the catalytic rate increased to 1.87 × 10− 2. Pre-treating PCP via cyclic voltammetry further enhanced the degradation process, yielding a catalytic rate of 2.7 × 10− 2 and 97.3% removal efficiency.