Preparation of TiO2 hollow spheres for DSSC photoanodes

• More photoactive A2 sites in the mesoporous TiO2 hollow spheres (MHS-TiO2) are observed by XANES.
• The N3 dye molecules being accessible to the mesopores of the MHS-TiO2 have relatively short loading time.
• The MHS-TiO2 photoanode has a better DSSC conversion efficiency than the nano-TiO2 one.

High crystallinity mesoporous TiO2 hollow spheres (MHS-TiO2) were prepared using the mesoporous carbon hollow sphere template. The MHS-TiO2 contains mainly nanostructured anatase. The mesopore of the MHS-TiO2 has a pore opening in the range of 400–600 nm. The refined extended X-ray absorption fine structure spectra indicate that the MHS-TiO2 possesses less the 1st-shell Ti–O coordination numbers than the nano-TiO2. More surface active species (A2 ((Ti=O)O4)) on the MHS-TiO2 are also observed by the component fitted X-ray absorption near edge structure spectroscopy. The MHS-TiO2 photoanode has a better DSSC conversion efficiency than the nano-TiO2 one by at least 40%. Note that the N3 dye molecules are accessible to the mesopores of the MHS-TiO2, and the loading time for N3 can be reduced by at least 70% if compared with those of the nano-TiO2.