Facile fabrication of Ag–Bi₂GeO₅ microflowers and the high photodegradable performance on RhB

In this work, a simple template-free one-pot solvothermal method was used to prepare hierarchical microflowers from Ag-modified Bi₂GeO₅ nanosheets. To characterize the phases and morphologies of the products, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area measurements were used. The characterization results showed the deposition of some spherical metal Ag particles ranging from 10 to 20 nm in size on the Bi₂GeO₅ nanosheets surface and the nanosheets-assembly of hierarchical microflowers with macroporous structures. Based on the Ag nanoparticles surface plasmonic resonance (SPR) and the hierarchical microflowers structure of Bi₂GeO₅, the Ag-modified Bi₂GeO₅ self-assembly microflowers exhibited excellent UV-light absorption. Photodegradable tests indicated that the decolorization rate of RhB with Ag-modified Bi₂GeO₅ (R_N = 0.1) microflowers was nearly 100% within 25 min, which was 1.5 times higher compared to that of unmodified Bi₂GeO₅ microflowers. Additionally, the photocatalytic performance stability tests demonstrated that the Ag-modified Bi₂GeO₅ hierarchical microflowers has excellent chemical stability. Investigations into the main oxidative species indicate that the main active species of Ag-modified Bi₂GeO₅ in RhB photodegradation are the superoxide radical (${\text{O}}_2^{\cdot -}$), and the ^·OH and h⁺ are also partially involved in the photocatalytic process. Finally, a possible photocatalytic mechanism for RhB photo-degradation onto Ag-modified Bi₂GeO₅ microflowers was proposed.