Hierarchical porous TiO2@C hollow microspheres: one-pot synthesis and enhanced visible-light photocatalysis

Hierarchical porous TiO2-carbon hybrid composites with a hollow structure were successfully fabricated by a one-pot low-temperature solvothermal approach in the presence of dodecylamine. The growth mechanism of the hierarchical hollow spheres was demonstrated to include the condensation of a carbon source and the co-instantaneous in situ hydrolysis of Ti-alkoxide, and the consequent assembly of TiO2@C hybrid nanoparticles on a self-conglobated template. As compared with the TiO2@C solid spheres (86%), the hierarchical TiO2@C hybrid hollow spheres exhibited an enhanced photocatalytic efficiency (97%) for the visible-light photooxidation of rhodamine B. Investigations demonstrated that the enhancement can be attributed to the hierarchical porous hollow structure. Moreover, the superoxide radical was detected as the main active species generated in the oxidation reaction of RhB over TiO2@C photocatalysts. A corresponding mechanism was also proposed for the photocatalysis process.