Michał Pacia has got his PhD degree. Congratulations!

Activation of O₂, H₂O and H₂O₂ in photoinduced electron transfer processes.

As part of the dissertation research was carried to recognize various aspects of activation of the O₂, H₂O and H₂O₂ presence of TiO₂ materials. In the case of anatase and rutile the influence of O₂ and H₂O₂ presence on ROS generation in the irradiated system was determined. It was proven that rutile, compared to anatase, performs better in both O₂ and H₂O₂ reduction. The influence of the exposed crystal facets on redox properties of materials were also investigated. The facets were put in an order (101) > (100) > (001) according to their activity in the H₂O₂ activation via reduction. Monocrystalline rutile materials, with exposed(110), (101) or (001) facets were also tested. The next step involved tests on surface modified TiO₂ materials. Proper approach to determining the EBG in the case of surface modified materials was established. Activity of materials modified with organic compounds coordinating to the surface of TiO₂ was tested. Additionally, a series of other semiconductors were investigated in terms of H₂O and H₂O₂ activation properties. One of the crucial parts of this work was to verify the suitability of available ROS detection and determination methods in the systems containing heterogeneous photocatalysts. Weaknesses of methods based on reduction of XTT and chemiluminescence of luminol have been shown. Both high selectivity and sensitivity of the method to analyze production of hydroxyl radicals based on the oxidation of TA was confirmed. By means of EPR spectroscopy, EDTA has been confirmed to have very good holes quenching properties.