Fabrication of pseudo-crystal nanostructures of TiO2 particles under UV-irradiation.
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.
Kim
Young-Kwan
YK
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
Yun
Seong-Hun
SH
Lee
Myoung-Jae
MJ
Shin
Yong-Hun
YH
Kim
Kyung-Min
KM
Kim
Sung-Ryong
SR
Lee
Seung Woo
SW
Lim
Jung-Hyurk
JH