Hierarchical TiO2/AgBr core/shell microspheres with enhanced visible light photocatalytic activity

TiO2/AgBr core/shell microspheres have been successfully synthesized via a two-step solvothermal process. The TiO2 core (1.5 µm in average diameter) is coated with a shell (100 nm in average thickness) consisting of AgBr nanoparticles of 6 nm in average size. The composite nanomaterials demonstrate much stronger light absorbance, narrower bandgap, and lower recombination rate of photogenerated electron–hole pairs than both bare TiO2 microspheres and pure AgBr nanoparticles, which endue it with much enhanced photocatalytic activity. The as-prepared TiO2/AgBr photocatalyst exhibits excellent photocatalytic degradation performance towards methylene blue (MB) under visible light irradiation, and 92% MB could be degraded in 90 min, which is much higher than that of bare TiO2 (11%) and pure AgBr (52%). TiO2/AgBr core/shell microsphere photocatalyst also demonstrates good reusability, and the photocatalytic activity has no obvious decrease after five cycles. This study may provide a new insight into the design and synthesis of visible light photocatalytic materials.