Hierarchical TiO_2/AgBr core/shell microspheres with enhanced visible light photocatalytic activity

摘要

TiO_2/AgBr core/shell microspheres have been successfully synthesized via a two-step solvothermal process. The TiO_2 core (1.5 μm in average diameter) is coated with a shell (100 nm in average thickness) consisting of AgBr nanopar-ticles 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 TiO_2 microspheres and pure AgBr nanoparticles, which endue it with much enhanced photocatalytic activity. The as-prepared TiO_2/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 TiO_2 (11%) and pure AgBr (52%). TiO_2/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.