Abstract
Highly uniform hollow spheres were assembled from truncated rhomboid anatase TiO 2 nanoparticles (HS), which were synthesized from the hydrothermal treatment of a NaF solution by using amorphous TiO 2 spheres as a precursor and template. The submicron hollow spheres with highly photocatalytic active surfaces exhibited excellent photocatalytic behavior. In this investigation, the factors that enhanced the photocatalytic performance were examined in terms of light harvesting, photoefficiency, and reaction activity. The photocatalytic performance was increased by a factor of approximately 1.5 for the scattering structure of submicron hollow spheres than that of nanofragments of submicron hollow sphere powder. The rate constant of anatase TiO 2 with specific photoactive surfaces at {001} and {101} was approximately six times higher than that of randomly exposed TiO 2 particles. Furthermore, a heterogeneous mixture of the submicron hollow spheres and micro-sized anatase TiO 2 (HSmicro-sized TiO 2 ) prohibited electron-hole recombination in the catalyst during the degradation reaction. The rate constant for the heterojunction system was 3.4times greater than that of the individual constituents. The rate constant for HSmicro-sized TiO 2 (k=0.175min -1 ) was 1.8times larger than that of commercial P25 (k=0.099min -1 ). HSmicro-sized TiO 2 is a promising photocatalytic material. Full of praise for hollow spheres: Factors that dominate the photocatalytic performance of our materials are light harvesting, photoefficiency, and the reaction activity of TiO 2 . A scattering structure enhanced the light harvesting (red square), a heterojunction improved the photoefficiency (blue square), and an active surface meliorated the reaction activity (green square). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.