Construction of amorphous SiO₂ modified β-Bi₂O₃ porous hierarchical microspheres for photocatalytic antibiotics degradation

This work describes the synthesis of porous hierarchical microspheres composed of amorphous SiO₂ and crystalline β-Bi₂O₃ (BSO) via a simple solvothermal process and subsequent calcination. Complementary physicochemical methods were applied to study the function of amorphous SiO₂, as well as the phase composition and morphology evolution of as-synthesized samples as a function of calcination temperature. The presence of amorphous SiO₂ contributed to form hierarchically structured β-Bi₂O₃ with enhanced thermostability. Moreover, the degradation of tetracycline hydrochloride (TC) under visible light irradiation was employed as a model reaction to evaluate the photocatalytic activity of as prepared materials. In consequence, both phase composition and morphology were found to be significant parameters for adjusting the photocatalytic performance of the synthesized samples. The fastest TC degradation at a low dosage of catalyst (0.2 g L^-1) was observed for the sample annealed at 400℃ which contains a highly crystalline β-Bi₂O₃ phase. The synergistic effect of the porous structure, excellent light absorption, and higher charge carrier separation and transfer efficiency is believed to be the reason for the optimal photocatalytic activity. This study offers a new method toward the fabrication of hierarchical porous structured β-Bi₂O₃ with enhanced thermostability for various applications.