Investigation of the optical property and photocatalytic activity of mixed phase nanocrystalline titania

Abstract

Mixed phase nanocrystalline titania are prepared by simple sol-gel method. The physico-chemical characteristics of the prepared nanoparticles are studied with X-ray diffraction, high-resolution transmission electron microscopy, RAMAN, BET, UV-Vis, steady state and time resolved photoluminescence. X-ray diffraction and Raman spectra clearly demarcate the anatase and rutile phase as both the phases give different diffraction patterns and Raman peaks. A comparison in the band gap indicates that pure anatase and rutile phase have band gap in the UV region, whereas a mixture of these phases has lower band gap and corresponds to the visible region. Steady state and time resolved photoluminescence are employed to understand the emissivity and carrier lifetime. The photocatalytic activity is evaluated by monitoring the degradation of phenol under visible light illumination. Due to the synergistic effect of mixed anatase and rutile phases, mixed phase nanocrystalline titania exhibit superior photocatalytic activity.

Annealing Control on the Anatase/Rutile Ratio of Nanostructured Titanium Dioxide Obtained by Sol-Gel

“…Generally, the values for all mixed-phase samples lies between these two values, and this lowering in the bandgap can be attributed to the presence of rutile, which induces additional states within the bandgap. The results shown here agree with those reported by other authors [35,36].…”

Recent Advancements in the Understanding of the Surface Chemistry in TiO2 Photocatalysis

“…In general, a correlation was found between longer decay times of ∆abs in transient UV absorption/reflection measurements and higher activities. For example, time-resolved emission quenching studies comparing different forms of titanium dioxide found an average decay constant of 1.99 ns for anatase and 1.65 ns for the less active rutile phase [106]. Likewise, it was found that decorating titanium dioxide with Pt islands, acting as electron sinks, extended the life time of trapped holes from the picosecond to the millisecond time scale, in correlation with the observation of higher activity [107].…”

Study of photocatalytic degradation of environmentally harmful phthalate esters using Ni-doped TiO2 nanoparticles

“…Hence, the charge transfer between the Ni 2? ions d-electron and TiO 2 conduction will appear (Paul and Choudhary 2014). The Ni 2?…”

“…The results obtained for the present studies are in correlation with this explanation already in the literature given (Aguilar et al 2013). The redshift of 0.2 mol% Ni-TiO 2 samples can be attributed to the charge transfer transitions between impurity band and the TiO 2 conduction band (Paul and Choudhary 2014). In TiO 2 , the valence band is composed of O-2p states and the conduction band is composed of Ti-3d states.…”