Photocatalytic degradation of organic compounds using TiO2 inverse opals nanostructures

CURTI M.; MENDIVE C.; GRELA M.A.; IVANOVA I.; SCHNEIDER J.; BAHNEMANN D.

Hannover

Workshop; ZFM Summer School; 2014

ZFM - Zentrum für Festkörperchemie und Neue Materialien, Leibniz Universitaet Hannover

Environmental remediation by means of wide band-gap semiconductors is a research topic which has been extensively addressed, and it is particularly centered on TiO2 owing to its many convenient properties. Nevertheless, its inability to absorb light from the visible region prevents it to efficiently take advantage of solar light.One relatively new and interesting strategy to improve its absorption capabilities is to structure the semiconductor as a photonic crystal. Interestingly, this approach allows reducing the group velocity of light within a certain energy range; for instance, photons within that range may therefore meet the chance of being absorbed by the semiconductor with higher probability. If this range of wavelength is properly selected to overlap with the spectral region where the semiconductor absorbs poorly, an enhancement of the photocatalytic activity, as compared to a non-structured situation, can be obtained.In this work inverse opal structures (close packed air spheres in a semiconductor particles matrix) are prepared in order to study their photocatalytic degradation of different organic model compounds. Mechanistic aspects concerning the photocatalytic activity of TiO2 are studied ranging from the strong interactions within the most primary steps, between the incoming photons and the semiconductor, e.g., the electron-hole pair creation and recombination, to the weak surface-surface interactions among the nanoparticles, contributing to the all-in-all photocatalytic transformation of the pollutant at the interface. Within this mechanistic framework, the enhanced photocatalytic activity of nanoparticulate TiO2 inverse opals will be discussed.