Journal article

Publication year: 2016

Pages: 10719-10726

Journal: Physical Chemistry Chemical Physics

Volume number: 18

Issue number: 16

ISSN: 1463-9076

eISSN: 1463-9084

Open access status: Hybrid

DOI Link: https://doi.org/10.1039/c5cp07115a

Publisher: Royal Society of Chemistry

Abstract: 
Charge carrier dynamics in phase pure Ba5Ta4O15 and in a Ba5Ta4O15-Ba3Ta5O15 composite have been studied by means of diffuse reflectance laser flash photolysis spectroscopy in the presence and absence of an electron donor, in order to reveal the reason for the improved photocatalytic performance of the latter. For the first time the transient absorption of trapped electrons with a maximum at around 650 nm and of trapped holes with a transient absorption maximum at around 310 nm is reported for tantalates. The decay kinetics of the photogenerated charge carriers could be fitted by second order reaction kinetics, and the direct recombination of the trapped electrons with the trapped holes was proven. In the absence of an electron donor, no difference in the decay behavior between the phase pure material and the composite material is found. In the presence of methanol, for the pure phase Ba5Ta4O15 the recombination of the charge carriers could not be prevented and the trapped electrons also recombine with the (CH2OH)-C-center dot radical formed via the methanol oxidation by the trapped holes. However, in the composite, the electron can be stored in the system, the (CH2OH)-C-center dot radical injects an electron into the conduction band of the second component of the composite, i.e., Ba3Ta5O15. Thus, the electrons are available for an extended period to induce reduction reactions.

Harvard Citation style: Schneider, J., Nikitin, K., Wark, M., Bahnemanna, D. and Marschall, R. (2016) Improved charge carrier separation in barium tantalate composites investigated by laser flash photolysis, Physical Chemistry Chemical Physics, 18(16), pp. 10719-10726. https://doi.org/10.1039/c5cp07115a

APA Citation style: Schneider, J., Nikitin, K., Wark, M., Bahnemanna, D., & Marschall, R. (2016). Improved charge carrier separation in barium tantalate composites investigated by laser flash photolysis. Physical Chemistry Chemical Physics. 18(16), 10719-10726. https://doi.org/10.1039/c5cp07115a