Visible Light-Induced Photocatalysis: Self-Fenton Degradation of p-ClPhOH Over Graphitic Carbon Nitride by a Polyethylenimine Bifunctional Catalyst

Deep degradation of organic pollutants by sunlight-induced coupled photocatalytic and Fenton (photo-Fenton) reactions is of immense importance for water purification. In this work, we report a novel bifunctional catalyst (Fe-PEI-CN) by codoping graphitic carbon nitride (CN) with polyethyleneimine ethoxylated (PEI) and Fe species, which demonstrated high activity during p-chlorophenol (p-ClPhOH) degradation via H2O2 from the photocatalytic process. The relationship between the catalytic efficiency and the structure was explored using different characterization methods. The Fe modification of CN was achieved through Fe-N coordination, which ensured high dispersion of Fe species and strong stability against leaching during liquid-phase reactions. The Fe modification initiated the Fenton reaction by activating H2O2 into center dot OH radicals for deep degradation of p-ClPhOH. In addition, it effectively promoted light absorption and photoelectron-hole (e-h+) separation, corresponding to improved photocatalytic activity. On the other hand, PEI could significantly improve the ability of CN to generate H2O2 through visible light photocatalysis. The maximum H2O2 yield reached up to 102.6 mu mol/L, which was 22 times higher than that of primitive CN. The cooperation of photocatalysis and the self-Fenton reaction has led to high-activity mineralizing organic pollutants with strong durability, indicating good potential for practical application in wastewater treatment.