]Figure. 1-1 TiO2 crystal structures rutile and anataseTiO2 is wide band gap energy n-type semiconductor ... materials (Figure. 1-1 anatase 3.2 eV rutile 3.0 eV)Especially, anatase type of TiO2 has widely received ... attention as a promising photocatalyst [4-7]TiO2 (Titania) has been widely investigated due to its application