title: Fabrication of pseudo-crystal nanostructures of TiO2 particles under UV-irradiation.
abstract: Colloidal titanium dioxide (TiO2) suspensions were synthesized by hydrolysis of titanium isopropoxide in the presence of acetic acid. When TiO2 colloids were subjected to bandgap excitation (ultraviolet [UV] irradiation), the colloidal solution exhibited yellow coloration, leading to the trapping of holes and electrons on the particle surfaces. The absorption spectra indicated a distinct absorption band in the UV and visible region. Dried-drop film of the UV-irradiated TiO2 suspension on the mica surface was characterized by scanning electron microscopy (SEM). SEM images showed that "crystal-like" network structures of TiO2 nanoparticles had formed dramatically on the solid surface. The resulting networks ranged in size from 100 nm to 500 nm and had crystal-growth patterns, while also having almost similar rectangular shapes. It seems that the individual particles, with electron or hole scavengers such as oxygen in ambient conditions, make contact with a number of neighbors, thereby forming self-assembled three-dimensional nanoparticle-based pseudo-crystalline structures.
authors.affiliation: Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
authors.forename: Young-Kwan
authors.initials: YK
authors.lastname: Kim
authors.forename: Seong-Hun
authors.initials: SH
authors.lastname: Yun
authors.forename: Myoung-Jae
authors.initials: MJ
authors.lastname: Lee
authors.forename: Yong-Hun
authors.initials: YH
authors.lastname: Shin
authors.forename: Kyung-Min
authors.initials: KM
authors.lastname: Kim
authors.forename: Sung-Ryong
authors.initials: SR
authors.lastname: Kim
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Lee
authors.forename: Jung-Hyurk
authors.initials: JH
authors.lastname: Lim