Improved structural stability of titanium-doped β-Bi₂O₃ during visible-light-activated photocatalytic processes

Due to its strong absorption to visible light and intrinsic polarizability, β-Bi₂O₃ could be a promising candidate for the visible-light-activated photocatalysis. However, its structural instability during a photocatalytic process prevents it from being used practically. In this work, titanium-doped β-Bi₂O₃ was synthesized by a hydrothermal method with subsequent calcination under 400 °C. Its crystal structure, photophysical property, and structural stability were investigated by using powder X-ray diffraction, Raman, infrared and diffuse reflectance UV–vis spectroscopies. The crystal structure of the titanium-doped β-Bi₂O₃ is analogous to β-Bi₂O₃. These two oxides exhibited comparable photocatalytic activities on the photodegradation of indigo carmine, rhodamine B, and methylene blue under visible-light irradiation. However, unlike β-Bi₂O₃, the titanium-doped β-Bi₂O₃ was quite stable during these photocatalytic reactions. The improvement in structural stability was attributable to the substitution of titanium species in the host crystal lattice. The current investigation results point toward the possibility of metal ion-doped bismuth oxides as efficient visible-light-activated photocatalysts.