Evaluation and Control of Photocatalytic Activities of Suspended Semiconductor Photocatalysts through Action Spectrum Analyses.

Abstract

The analyses of the wavelength-dependent photocatalytic activity by taking action spectra are useful for the evaluation of an active cryst. phase of semiconductor photocatalysts that contain two or more polymorphic cryst. phases and/or the different chem. compns. of different photoabsorption characteristics. The action spectra of photocatalytic reactions of H2 evolution, acetic acid decompn., and Ag deposition were measured by using powd. titanium (IV) oxide (TiO2) photocatalysts of anatase-rutile mixts. The discrimination of an active cryst. phase in powd. photocatalysts was performed by the comparison between the action spectra of photocatalytic reactions and the diffuse reflectance spectra of TiO2 powders. The active phase was different depending on the kinds of photocatalytic reactions even if the same mixed TiO2 powders were used as photocatalysts; the photocatalytic activity of H2 evolution was not so different in the anatase and rutile phases included in the mixed TiO2 powders, while anatase or rutile phases were more active for the acetic acid decompn. or Ag deposition reactions, resp. [on SciFinder (R)]