For mesoporous TiO2 preparation, tetraisopropylorthotitanate
(TIPT, Tokyo Chemical Industry Co. Ltd.) was
mixed with the same mole of ACA (Nacalai Tesque Inc.) to
slowdown the hydrolysis and the condensation reactions
[11–13]. Subsequently, 0.1 M LAHC (Tokyo Chemical
Industry Co.) aqueous solution (as the surfactant, pH 4–4.5)
was added in the solution (molar ratio of TIPT to LAHC was
4), and it was stirred at room temperature for 1 h. After
stirring at 40 8C for 24 h, it was put into an oven at 80 8C for
1 week. The alcohol by-product was removed by drying at
80 8C for 24 h, followed by calcinations at 400 8C for 4 h
(Fig. 1). Mesoporous CeO2, ZrO2, and HfO2 nanopowders