Solvothermal synthesis of tantalum(V) oxide nanoparticles and their photocatalytic activities in aqueous suspension systems

Citation
H. Kominami et al., Solvothermal synthesis of tantalum(V) oxide nanoparticles and their photocatalytic activities in aqueous suspension systems, PHYS CHEM P, 3(13), 2001, pp. 2697-2703
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
ISSN journal
1463-9076 → ACNP
Volume
3
Issue
13
Year of publication
2001
Pages
2697 - 2703
Database
ISI
SICI code
1463-9076(2001)3:13<2697:SSOTON>2.0.ZU;2-S
Abstract
Tantalum(v) oxide (Ta2O5) powders were synthesized by a solvothermal reacti on of tantalum pentabutoxide (TPB) in toluene at 473-573 K in the presence of water. Ta2O5 powder with a large surface area (> 200 g(-1)) was obtained at 473 and 523 K, and its X-ray diffraction patterns showed no clear peaks of crystallites, while crystalline beta -phase Ta2O5 was obtained in the s olvothermal process at 573 K. Post-calcination of the amorphous Ta2O5 at 97 3 K also induced crystallization into the beta -phase. These amorphous and crystalline Ta2O5 particles were platinized and then used for photocatalyti c production of hydrogen from 2-propanol in aqueous solution under deaerate d conditions by irradiation at a wavelength > 300 nm. As-synthesized amorph ous and crystalline beta -phase samples exhibited negligible rates of hydro gen evolution, whereas crystalline beta -phase samples formed by post-calci nation showed higher activity. Calcination of amorphous Ta2O5 prepared by h ydrolysis of TPB under atmospheric pressure also increased the rate, which is, however, ca. one third of that of Ta2O5 obtained via the solvothermal r oute. Mineralization of acetic acid under aerated conditions was conducted as a test reaction for photocatalytic decomposition of organic compounds. A lso, in this reaction system, bare (not platinized) solvothermal Ta2O5 exhi bited a higher rate of CO2 formation than other Ta2O5 samples. Photoirradia tion at > 200 nm onto an aqueous 2-propanol suspension of platinized Ta2O5 under deaerated conditions yielded hydrogen and acetone in an early stage, but CO2 was liberated by prolonged irradiation, suggesting that decompositi on of acetone to CO2 proceeds even under deaerated conditions.