Influence of thermal annealing on the photo catalytic properties of TiO2 nanoparticles under solar irradiation

Abstract

Nanosized TiO 2 particles have been synthesized by a sol-gel method and studied for their thermal, structural, optical, morphological, and photocatalytic properties at different annealed temperatures. The results of the structural analysis show the anatase phase of TiO 2 at 400°C, the mixed phase at 700°C, and pure rutile phase at 800°C. The red-shift of absorption edges and band gap reduction are the two factors suggested by UV-Vis spectra, confirming the phase change of TiO 2 from anatase to rutile on annealing at 800°C. The PL emission results of annealed products exhibit enhanced visible emissions on annealing as a result of increased oxygen vacancies. The photocatalytic activities of the annealed products were analyzed against the organic dye brilliant green (BG). Among the all, TiO 2 annealed at 700°C shows an enhanced photocatalytic performance against the organic dye BG.

Photodegradation of organic dyes based on anatase and rutile TiO2nanoparticles

“…20 The absorption peak near 3342 cm À1 was attributed to the presence of stretching mode of hydroxyl groups mostly present with titania nanoparticles or in surfactants. 39,40 The main peaks due to C-H symmetric and asymmetric stretching, C]O stretching and C-O stretching frequencies were observed near 2920 cm À1 , 1638 cm À1 , 1050 cm À1 respectively. The presence of peak at 1519 cm À1 in case of titania NPs sintered at 100 C clearly differentiate and conrms the presence of N-C stretching as the TiO 2 nanoparticles are capped with PVP.…”

“…The peak observed near 1626 cm À1 corresponds to the interaction between the Ti-O network and the ionised COO of the myristic acid. [39][40][41] All major peaks from the IR spectrum of titania sintered at 800 C (Fig. S5IV †) are disappeared indicating complete evaporation of the surfactant molecules from titania surface.…”

Hierarchical nano ZnO-micro TiO2 composites: High UV protection yield lowering photodegradation in sunscreens

“…The overlapping bands are attributed to the electron-hole recombination across the conduction band and the valence band (band-gap) and to shallow surface traps emissions due to oxygen vacancies (Vo) trap states [28,29]. The band at ~580nm comes from intra gap surface states originated from Ti 4+ ions which stay adjacent to oxygen vacancies [30]. Oxygen vacancies are considered as the most common defects that act as radiative centers in luminescence processes [31].…”

A review of scandium–hafnium doped TiO2 nanocrystals

“…The catalytic performance of a catalyst mainly depend upon the surface area. It increases the probability of degradation by increasing the pore size and pore volume [18].…”