Size-selective photocatalytic reactions by titanium(IV) oxide coated with a hollow silica shell in aqueous solutions.
A novel core-shell composite photocatalyst, commercially available titanium(IV) oxide (TiO(2)) particles directly incorporated into a hollow amorphous silica shell, was fabricated by successive coating of TiO(2) with a carbon layer and a silica layer followed by heat treatment to remove the carbon layer. The composite induced efficient photocatalytic reactions when relatively small substrates were used, such as methanol dehydration and decomposition of acetic acid, without any reduction in the intrinsic activity of original TiO(2), but did not exhibit efficient photocatalytic activity for decomposition of large substrates, methylene blue and polyvinyl alcohol. The unique size-selective properties of the composites are due to their structural characteristics, i.e., the presence of a pore system and a void space in the silica shell and between the shell and medial TiO(2) particles, respectively. The loading of alkylsilyl groups on the surface of the composite led to highly photostable floatability: the floated sample also induced efficient photocatalytic reaction for decomposition of acetic acid while retaining floatation at the gas/water interface.
Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, 560-8531, Japan. sikeda@chem.es.osaka-u.ac.jp
Shigeru
S
Ikeda
Hideyuki
H
Kobayashi
Yoshimitsu
Y
Ikoma
Takashi
T
Harada
Tsukasa
T
Torimoto
Bunsho
B
Ohtani
Michio
M
Matsumura
D002384:Catalysis; D010316:Particle Size; D010777:Photochemistry; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D012996:Solutions; D014867:Water; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium