Exposed crystal surface-controlled rutile TiO2 nanorods prepared by hydrothermal treatment in the presence of poly(vinyl pyrrolidone)

Rutile TiO2 particles with specific exposed crystal faces were prepared by hydrothermal treatment of titanium trichloride (TiCl3) solution with poly(vinyl pyrrolidone) (PVP) as a shape-control reagent. Crystal phase, shape, and size of TiO2 particles were found to be greatly dependent on the concentration of PVP in the solution. The exposed crystal surface of TiO2 was controlled by changing the concentration of PVP in TiCl3 and NaCl solutions. The prepared TiO2 particles were characterized by TEM, SEM, XRD, and specific surface area measurements. The photocatalytic activity of the synthesized TiO2 particles was evaluated by decomposition of acetaldehyde and toluene in gas phase. The synthesized TiO2 particles showed higher photocatalytic activity for degradation of acetaldehyde and toluene than did commercial TiO2 particles (MT-600B). However, the tendency of photocatalytic activities of the synthesized TiO2 particles for degradation of acetaldehyde in gas phase was different from that for degradation of toluene. From the photodeposition of Pt and PbO2, we propose that the (1 1 0) face provides reductive sites and that the (1 1 1) face provides oxidative sites. The results suggest that the crystal faces facilitate the separation of electrons and holes, resulting in improvement in photocatalytic activity.