Synthesis of Core-shell Structured Ti@TiO2/BiOBr Microspheres with Improved Photocatalytic Performance

Titanium microspheres served a dual role in this study. First, they acted as supporting materials for TiO 2 /BiOBr photocatalysts. Second, they provided a low-cost precursor for titanium dioxide preparation. The growth of core-shell structured Ti@TiO 2 microspheres was realized using a hydrothermal method in NaOH solution. By varying the concentration of NaOH solution, TiO 2 nanowires with different morphologies were fabricated. A comprehensive characterization of the samples using field-emission scanning electron microscopy, X-ray diffraction measurements, and energy-dispersive X-ray analysis revealed that TiO 2 nanostructures formed a well-coated layer on titanium microspheres, demonstrating an anatase crystal structure. The photocatalytic performance of the obtained core-shell structured Ti@TiO 2 microspheres was studied through the photocatalytic degradation of Rhodamine B (RhB) solution. The results demonstrated that the sample prepared in NaOH solution with the concentration of 7 M exhibited the best photocatalytic performance, achieving an RhB removal efficiency of nearly 100% within 100 min under simulated light irradiation. In order to further improve the photocatalytic performance of the prepared samples, BiOBr was loaded on the surface of TiO 2 nanowires via a solvothermal method, yielding core-shell structured Ti@TiO 2 /BiOBr heterojunction photocatalysts, consisting of a metallic Ti core and a composite TiO₂/BiOBr shell. The catalysts demonstrated a significant enhancement in photocatalytic performance compared with core-shell structured Ti@TiO 2 microspheres, achieving nearly complete degradation of RhB solutions within 30 min. Furthermore, the photocatalyst maintained 91.92% of its activity after three consecutive cycles.