Photocatalytic hydrogen of CH/sub 3/CCH with H/sub 2/O on small-particle TiO/sub 2/: size quantization effects and reaction intermediates

Journal Article · Thu Jul 30 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100300a021· OSTI ID:6189498

Anpo, M; Shima, T; Kodama, S; Kubokawa, Y

Photocatalytic hydrogenation reactions of CH/sub 3/CCH with H/sub 2/O were investigated with TiO/sub 2/ catalysts of extremely small particle size. Photocatalytic activity increased as the diameter of the TiO/sub 2/ particles becomes smaller, especially below 100 A. Absorption and photoluminescence spectra of catalysts exhibit blue shifts as the diameter of TiO/sub 2/ becomes smaller, also especially below 100-A particle size, suggesting that a size quantization effect is operating. Photoformed, carbon-centered radical species resulting from the fission of the carbon-carbon bond of alkyne molecules and Ti/sup 3 +/ ions as trapped electrons were directly in observable. The different dependence of the yields on the particle diameter of TiO/sub 2/ catalyst suggests that the differences in photocatalytic activity arise from the differences in the reactivity but not in the physical properties such as the surface area of these catalysts. This demonstrates a size quantization effect at extremely small TiO/sub 2/ particles. Reduction of size might result in some electronic modification of TiO/sub 2/ to produce an enhancement of the activities of electrons and holes, and/or a suppression of the radiationless transfer of absorbed photon energies.

• Research Organization: Univ. of Osaka Prefecture, Japan
• OSTI ID: 6189498
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:16; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION SPECTROSCOPY
ALKENES
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
COHERENT SCATTERING
DATA
DIFFRACTION
EFFICIENCY
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
INFORMATION
LUMINESCENCE
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
QUANTITY RATIO
QUANTUM EFFICIENCY
RADICALS
REACTION INTERMEDIATES
SCATTERING
SIZE
SPECTROSCOPY
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
WATER
X-RAY DIFFRACTION