Reinis Drunka

Preparation of Au, Pt, Pd and Ag Doped TiO2 Nanofibers and their Photocatalytic Properties under LED Illumination

In the present work formation of active TiO2 nanofibers in microwave-assisted synthesis and their modification with Au, Pt, Pd and Ag nanoparticles were studied. Anatase nanopowder and 10M KOH solution were used as raw materials. Microwave-assisted synthesis permitted to obtain TiO2 nanofibers and nanowires with a diameter of 10nm and a specific surface area 158.5m2/g. Chemical deposition method were used to modify TiO2 nanofibers with precious metal nanoparticles. After modification, specific surface area decreased and were in range 73.1 – 74.7m2/g. Photocatalytic activity was determined by degradation of the methylene blue (MB) solution under visible light irradiation. High intensity LED lamp was used as light source. The obtained samples showed higher photocatalytic activity with respect to pure TiO2 nanofibers. The doped TiO2 nanofibers were appropriate for degradation of harmful organic compounds as well as for hydrogen production by water splitting.

Au Supported on the TiO2-nanofibers as Novel Catalysts for Glycerol Oxidation

Composites of Au supported on the TiO2-nanofibers (Au/NF-TiO2) were synthesized and tested in glycerol oxidation processes. TiO2-nanofibers were prepared by a microwave-assisted hydrothermal synthesis method. Chemical deposition method was used for nanofibers modification with Au nanoparticles. Oxidation of aqueous glycerol solutions by molecular oxygen in the presence of Au/NF-TiO2 nanocomposites was performed. It was found that Au/NF-TiO2 composites are catalytically active in alkaline glycerol water solutions. The main product of glycerol catalytic oxidation was glyceric acid, by-products were – tartronic, lactic, glycolic, oxalic, acetic and formic acid. It was shown that Au/NF-TiO2 catalysts’ activity and selectivity depend on Au weight loading, glycerol/Au molar ratio, oxygen pressure and NaOH initial concentration. The best result was achieved using the 0.5 wt%Au/NF-TiO2 catalyst: selectivity by glyceric acid was 76% with glycerol conversion 100%.

Microwave Synthesis and Properties of Thin Layer Pt Modified TiO2 Nanofibers Coating

In the present work formation of macro-size TiO2 nanofiber layers in microwave synthesis were studied. Anatase nanopowder and 10M KOH solution were used as raw materials. Microwave assisted synthesis method permitted to obtain TiO2 nanofibres containing individual nanowires with a diameter of 5nm and a specific surface area up to 129m2/g. Macro size layer of TiO2 nanofibers was obtained on the surface of microwave vessel. Total surface area covered with TiO2 was about 390cm2. Modification with platinum allows to increase photocatalytical activity of TiO2 macro size fiber layer up to 94.4% in UV irradiation and up to 11.6% under visible light irradiation.