Construction and Synthesis of Ternary rGO/COF-C4N/NH2-Bi2O3 Heterojunctions for Efficient Photocatalytic Degradation of Chlorophenol

Abstract

A new type of highly efficient ternary rGO/COF-C4N/NH2-Bi2O3 heterojunctions was designed and synthesized by solvothermal and ultrasonic methods, and was applied to photocatalytic degradation of chlorophenol in water. The results show that the photocatalytic activity and stability of rGO/COF-C4N/NH2-Bi2O3 for the degradation of o-chlorophenol (2-cp) was significantly increased as compared with that of pure Bi2O3, COF-C4N, and COF-C4N/NH2-Bi2O3. The photocatalytic degradation rate for 2-cp by rGO/COF-C4N/NH2-Bi2O3-5% get to 83.7% and 97.4%, and the highest degradation rate constants are 0.0072 min⁻¹ and 0.0158 min⁻¹ under visible light and full light, respectively. The ternary photocatalyst rGO/COF-C4N/NH2-Bi2O3-5% maintained its performance even after four consecutive cycles, only decreasing by 5% of its degradation rate. The degradation experiments for other chlorophenols pollutants under visible light displayed that this ternary heterojunction is mainly applicable to the degradation of 2-cp and 2, 4-dcp, but inefficient for cp, 3-cp, and 4-cp. The degradation rates of 2, 4-dcp could reach 85.1% under visible light. Based on the analysis of band structure, free radical trapping experiment and photoelectrochemical properties, the photocatalytic degradation mechanism of chlorophenols by type II rGO/COF-C4N/NH2-Bi2O3 heterojunction was proposed, in which h+ and ∙OH- have main influence on the degradation activity, and the rGO plays an important role in improving the charge transfer and separation. This work provides a choice for the effective removal of chlorophenols wastewater by photocatalysis