Charge Carrier Recombination and Trapping in different TiO2 Photocatalysts: A Time Resolved Study in the Nanosecond time scale

SCHNEIDER J.; MENDIVE C.; BAHNEMANN D.

Thessaloniki

Congreso; 8th European Meeting on Solar Chemistry and Photocatalysis: Environmental Applications (SPEA8); 2014

Natural Resources and Renewable Energies Laboratory - Centre for Research & Technology Hellas

In the present study, two techniques have been applied for the investigation of different TiO2 crystal phases, i.e., Laser Flash Photolysis-Spectroscopy (LFPS) to monitor the reaction dynamics of trapped charge carriers and Time Resolved Microwave Conductivity (TRMC) for the tracking of mobile charge carriers, respectively. The observed kinetics of the transient absorption and of the microwave conductivity decays were assigned to the recombination of the trapped holes with the mobile bulk electrons. Assuming that the trapped holes are entities with quantized energy states λ, the recombination can proceed via two mechanisms: R1 and R2, corresponding to λ1 and λ2, respectively. In any of these recombination mechanisms the mobile electrons need to have a mobility associated with the respective λ-value matching either λ1 or λ2.