Naslov
Preparation and properties of TiO2 based one dimensional nanostructures decorated by Ag and modified in reduction atmosphere

Autori
Gajović, Andreja ; Plodinec, Milivoj ; Grčić, Ivana ; Čeh, Miran ; Willinger, Marc

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
TO-BE Spring Meeting 2015 University of Aveiro, Book of Abstract / Ferreira, Paula ; Fittipaldi, Rosalba - Aveiro : Department of Materials and Ceramic Engineering, University of Aveiro, 2015, 67-67

Skup
TO-BE Spring Meeting 2015 University of Aveiro

Mjesto i datum
Aveiro, Portugal, 30.03.2015. - 02.04.2015

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
TiO2; 1-D nanostructures; modification

Sažetak
TiO2-based nanostructures have been extensively investigated materials over the past two decades, because of their promising physical and chemical properties, such as a high specific surface area, the low costs of synthesis, a high photo-activity and environmental stability. Because of these properties the titania nanostructures can be used for photo-catalysis, in solar cells (DSSC) and sensors. Since TiO2 has a relatively large band- gap (3.2 eV for anatase and 3 eV for rutile phase), it can absorb light and behave as photo- catalytically active only under irradiation with UV light. So, one of the key parameters necessary to develop such properties in the visible and near-IR regions is to optimize the band-gap of TiO2-based materials towards the bandgap of monocrystal silicon. In this study we use Ag nanoparticles and hydrogenation to manipulate with the TiO2-based nanotubes properties. Titanate, H2Ti3O7, nanotubes (TiNTs) were synthesized using the hydrothermal method as bottom up approach. Alternatively, TiO2 nanotubes array (TiONTA) was synthesized by anodization as top down approach. In case of decorated nanotubes the silver particles were obtained by the photo- reduction of AgNO3 under UV light. Pure and Ag- decorated nanotubes were additionally heat treated in hydrogen. For the structural characterization we used conventional and analytical transmission electron microscopy (TEM) and scanning electron microscopy (SEM), techniques, X-ray diffraction (XRD) and Raman spectroscopy. Using UV–ViS-NIR spectroscopy we studied band gaps and the photo- catalytic activity on model organic compounds (wastewater) for all the samples before and after hydrogenation. We found that decoration of TiNT and TiONTA with Ag broadened the light absorption also in visible range due to the surface plasmon resonance of Ag nanoparticles. Since the shape and diameter of the Ag nanoparticles on TiO2 surface vary, the frequency of their plasmonic oscillations covers a wide range, permitting absorbance of visible and UV light over a wide range. However, the hydrogenation at high temperature was shown as essential to considerably increase the absorption of light in the visible and near-IR regions. This is a consequence of the synergetic effects between the silver and the defects at the surface of TiO2 nanoparticles (the most probably oxygen vacancies) that increase the efficiency of the formation of electron–hole pairs and the charge transfer to the surface of the nanoparticles.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

POVEZANOST RADA