N-Doped TiO2 Hollow Spheres with Enhanced Visible-Light Photocatalytic Activity for Water Purification

N-doped TiO2hollow spheres (labeled as NTH) were prepared using hydrophilic colloidal carbon spheres as template in conjunction with the sol-gel method. The hollow spheres were characterized by XRD, SEM, UV-Vis and XPS. Photocatalytic activity of N-doped TiO2hollow spheres was determined by degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2) under visible light irradiation. The photocatalytic activity of the sample enhanced a lot compared to commercial P25 TiO2. The apparent rate constant of the N-doped TiO2hollow spheres was almost 10 times as that of P25 TiO2.