Naslov
TiO2 nanotubes arrays decorated by Ag and modified in reduction atmosphere for photocatalytic application using visible light

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

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, neobjavljeni rad, znanstveni

Izvornik
EMC2016 / - , 2016

Skup
The 16th European microscopy congress

Mjesto i datum
Lyon, Francuska, 28.08.2016. - 02.09.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
TiO2 nanotubes arrays; Ag nanoparticles; photocatalysis

Sažetak
TiO2 nanostructures with promising physical and chemical properties, such as a high specific surface area, a high photo-activity and environmental stability, but also the low costs of synthesis inspire numerous study over the past three decades. Titania nanostructures can be used for photo- catalysis, in solar cells (DSSC) and sensors, still it can absorb light and behave as photo-catalytically active only under irradiation with UV light since TiO2 has a relatively large band-gap (3.2 eV for anatase and 3 eV for rutile phase). So, one of the key parameters necessary to develop enhanced photocatalytic properties in the visible and near-IR regions is to optimize the band-gap of TiO2 materials towards the bandgap of monocrystal silicon. In our study we use Ag nanoparticles and hydrogenation to manipulate with the bandgap, photo- absorption of TiO2 nanotubes with the aim to enhance photocatalytic properties. TiO2 nanotubes array (TiNTA) was synthesized by anodization of titanium foils as broadly used method for production of nanotubes arrays with different morphology and dimensions of nanotubes. In case of decorated nanotubes, the silver particles were obtained by the photo-reduction of AgNO3 under UV light. Pure and silver-decorated nanotubes were additionally heat treated in hydrogen. For the structural characterization we used conventional and analytical transmission electron microscopy (TEM) including high angle annular dark field imaging (HAADF), 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 TiNTA with Ag broadened the light absorption also in visible range due to the surface plasmon resonance of Ag nanoparticles. Ag nanoparticles with different shapes and diameters are attached on TiO2 array surface (Fig. 1) as well as inside the nanotubes (Fig. 2). Therefore, the frequency of their plasmonic oscillations covers a wide range, permitting absorbance over a visible and UV part of solar spectrum. Moreover, 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