Preparation and Visible Light Catalytic Performance of Layered Ag Double Modified Bi₂WO₆ with One-step Solvothermal Method

Using Bi(NO₃)₃·5H₂O, Na₂WO₃·2H₂O and AgNO₃ as raw materials, Ag doped and Ag nanoparticle modified Ag/Bi₂WO₆ composite photocatalysts were prepared by using a one-step solvothermal method. Structure and properties of the samples were characterized by using XRD, SEM, XPS, TEM, HRTEM, UV-Vis DRS, PL, etc. Under simulated sunlight irradiation conditions, the photocatalytic performance and mechanism of Bi₂WO₆ and Ag/Bi₂WO₆ were studied by using methyl orange (MO) for the degradation experiment. The Ag/Bi₂WO₆ has a circular layered structure formed through the stacking of nanosheets. Ag exists in two forms, entering the Bi₂WO₆ lattice through doping and incorporation with Bi₂WO₆ as composite. With Ag modification, the band gap width of Bi₂WO₆ was reduced from 2.65 eV to 2.25 eV, resulting in a decrease in fluorescence intensity. Compared with Bi₂WO₆, Ag/Bi₂WO₆ has high degradation efficiency on the degradation of methyl orange. By using Ag/Bi₂WO₆ with 2% Ag, the degradation rate reached 98.27%, after 10 min, corresponding to a degradation rate constant of 0.4359 min^-1, which is about 10 times that of Bi₂WO₆. Even after five cycles, the degradation rate remained above 90% for Ag/Bi₂WO₆, indicating its high stability. The dual modification of Ag broadened the light absorption range of Bi₂WO₆, promoted the separation of photo generated charge carriers, and thus enhanced the photocatalytic performance.