Naslov
Thermal stability of titanate nanotubes

Autori
Blažic, Roko ; Minga, Iva ; Kurajica, Stanislav

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

Izvornik
XI. Susret mladih kemijskih inženjera, Knjiga sažetaka / Matijašić, Gordana - Zagreb : Hrvatsko društvo kemijskih inženjera i tehnologa (HDKI), 2016, 73-73

ISBN
978-953-6894-55-0

Skup
XI. Susret mladih kemijskih inženjera

Mjesto i datum
Zagreb, Hrvatska, 18.02.2016. - 19.02.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
Titanate nanotubes

Sažetak
The synthesis and characterization of various inorganic nanotubes has become an important research subject within the latest years. Among them, special attention has been payed to titanate nanotubes due to their potential applications as photocatalyst, photovoltaic cells, semiconductor devices, etc. The purpose of the present work is to provide information on the thermal stability as well as thermally induced structural changes of titanate nanotubes. Titanate nanotubes were prepared by hydrothermal treatment of TiO2 powder in 10 M NaOH aqueous solution at reaction temperature of 135 °C for 72 h, followed by HCl rinsing. FESEM analysis revealed that strongly aggregated nanotubes with approximate diameter of 10 nm and several hundred nanometers in length were prepared. According to XRD data the crystal structure of the nanotubes is analogous to that of H2Ti2O5×H2O (ICDD PDF No. 47-0124). In order to gain insight in thermal stability of the titanate nanotubes, DTA and TGA were performed. The DTA curve shows two endothermic peaks at approximately 100 and 150 °C that are characteristics for the evaporation of surface and interlayer adsorbed water molecules. Upon subsequent heating dehydroxylation takes place causing the collapse of nanotubes and formation of anatase. Therefore, small exothermic peak at approximately 500 °C is attributed to the transformation to anatase. TGA curve showed mass loss in interval from room temperature to 400 °C of about 18% comprising removal of adsorbed, intercalated and crystal water. Deeper insight in thermal transformations of prepared titanate nanotubes was obtained through XRD and FTIR analysis. Thermal treatment of titanate nanotubes was interrupted at various temperatures between 135 and 1000 °C and the obtained samples were analyzed. Slight shift of this diffraction peaks towards higher 2θ value (shorter interlayer distance) after calcination at 400 °C was attributed to the dehydroxylation and the commencement of structural changes since the transformation of titanate nanotubes to anatase begins above 400 °C and it is almost complete at 500 °C. Rutile appears after thermal treatment at 700 °C while complete conversion of anatase to rutile is completed at 900 °C. FTIR spectra exhibit a broad band centered at about 3, 380 cm-1 which is attributed to the stretching vibration of the hydroxyl groups (O–H), as well as band at ~1, 630 cm-1 assigned to the H-O-H bending vibration, indicating the presence of surface hydroxyl groups and water molecules adsorbed on the surface and in the interlayer space of the nanotubes. The fact that bands attributed to water appear in each spectrum, regardless of heat treatment temperature, points out to a reversibility of water physisorption phenomenon. All bands in the 500-400cm-1 interval could be attributed to Ti-O-Ti vibrations of the interconnected octahedra. Considering XRD data it is quite obvious that the band at 440, 415 and 465 cm-1 could be attributed to Ti-O-Ti vibrations in titanate nanotubes, anatase and rutile, respectively.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne tehničke znanosti

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