Visible-light photoelectrocatalysis/H₂O₂ synergistic degradation of organic pollutants by a magnetic Fe₃O₄@SiO₂@mesoporous TiO₂ catalyst-loaded photoelectrode

In this paper, we describe a method for photoelectrocatalysis (PEC)/H2O2 synergistic degradation of organic pollutants with a magnetic Fe3O4@SiO2@mesoporous TiO2 (FST) photocatalyst-loaded electrode. At optimal conditions of pH 3.0, 2.25% H2O2, working electrode (fixed FST 30 mg) potential +0.6 V (vs. SCE), and 10 mg L-1 of all experimental pollutants, the FST PEC/H2O2 synergistic system exhibited high activity and stability for the removal of various organic pollutants under visible light with comparable degradation efficiencies, including MB (98.8%), rhodamine B (Rh B, 96.7%), methyl orange (MO, 97.7%), amoxicillin (AMX, 83.9%). Moreover, this system obtained TOC removal ratios of 83.5% (MB), 77.9% (Rh B), 80.2% (MO), 65.5% (AMX) within 8 min. The kinetic rate constants of the PEC/H2O2 synergistic system were nearly 53 and 1436 times higher than that of the PEC process and H2O2 photolysis under visible light, respectively. Furthermore, the main reactive oxidant species (˙OH, ˙O2-) were studied and enhanced mechanisms of the photocatalytic-electro-H2O2 coupling system were proposed. This work brings new insights to efficiently purify organic pollutants by PEC coupled with peroxide under solar light illumination.