Synthesis of Z-scheme AgVO/AgVO/GO nanocomposites for photocatalytic degradation of DDT under visible light.

The direct Z-scheme AgVO/AgVO/GO (AVGZ) nanostructure was successfully synthesized using a hydrothermal method with microwave-assisted techniques. The obtained AVGZ catalyst was characterized by XRD, TEM, EDX, UV-Vis, PL, and XPS methods. The characterization results showed that under controlled pH conditions, the orderly stacking of vanadium oxide tetrahedron formed AgVO nanoparticles (NPs) on the surface of AgVO nanorods (with a diameter of 50-200 nm). Interestingly, the AVGZ exhibited absorbance in the visible light region at 470-550 nm wavelengths. The photocatalytic performance of AVGZ was evaluated by the degradation of dichloro-diphenyl-trichloroethane (DDT) under LED visible light irradiation. Compared to the AgVO/AgVO nanostructure material, AVGZ showed much higher activity in the degradation of DDT under the same reaction conditions. The optimal conditions were determined to be a catalyst concentration of 0.5 g L, pH 6.0, and reaction time of 4 hours, achieving a DDT degradation efficiency of 95.46%, according to the analysis using the response surface methodology (RSM) based on the central composite design (CCD) method. The DDT degradation efficiency was higher compared to AgVO/GO (89.4%) and AgVO (82.1%), respectively. Scavenging experiments were conducted to study the photocatalytic mechanism using the spin trapping technique (EPR). The results indicated that ·OH and ·O radicals were the primary oxidizing agents in the photocatalytic reaction process on the AVGZ catalyst. The formation of a heterojunction and the addition of GO accelerated electron-hole pair separation, enhancing the durability and efficiency of the photocatalysts. Furthermore, the Z-scheme mechanism of the AVGZ photocatalyst was also proposed, demonstrating its potential application for DDT degradation under LED visible light.