Anatase and brookite TiO₂with various morphologies and their proposed building block

Abstract

In this work, brookite TiO 2 has been synthesized by a simple hydrothermal approach using sodium titanate as a precursor in the presence of a sodium fluoride aqueous solution. The ratio of brookite and anatase TiO 2 can be tailored by the NaF concentration. In a concentrated NaF solution, high quality brookite TiO 2 was acquired. Pure anatase nanoparticles were obtained in only deionized water.Moreover, the morphology and size of brookite TiO 2 can be tailored by using various acid treated titanates which influence the stability of the building blocks and nucleation points of TiO 2 . Micro-sized flower-like brookite, submicro-sized urchin-like brookite and brookite nanorods with anatase nanoparticles were obtained. The micro-sized flower-like brookite remains the same shape and phase even at 800°C, whereas obvious grains were formed on the matrix with brookite, rutile and anatase mixture phases at 900°C. On the other hand, as the submicro-sized urchin-like brookite was heated, a rutile phase appeared at 750°C and 100% grain-like rutile was obtained at 900°C.

UV and Visible light photodegradation of methylene blue with graphene decorated titanium dioxide

“…It can be seen in figure 1(a) that the TiO 2 anatase phase together with a small fraction of brookite phase [14] (peak centered at 30.8°corresponding to (121) plane and marked with a star) were obtained from the HT process; the phases percentages were found to be 94% anatase and 6% brookite. Brookite phase percentage was estimated by the methodology used in [15] and [16] 1(c)), which means that graphene layers stack together due to the increasing temperature. Figure 1(d) shows a TEM micrograph of a graphene sample.…”

Fabrication of mixed-crystalline-phase spindle-like TiO2 for enhanced photocatalytic hydrogen production

“…As can be seen, the diffraction peaks of the MC TiO 2 at 2θ = 25.3°, 37.8°, 48.2°, 53.9°, 55.1°, and 62.7° belong to the anatase phase of TiO 2 [20,21]. It is worth noting that the small peak at 2θ = 30.8° is the (121) reflection of the brookite phase of TiO 2 [22]. As the calcination temperature increases, the intensity of the characteristic brookite peak decreases.…”

Synthesis of Pure Brookite Nanorods in a Nonaqueous Growth Environment

“…Growth of brookite under acidic conditions has also been consistently reported when the water soluble Ti complexes are replaced by TiCl 4 [14,[21][22][23]. The driving potential of the pH value and other parameters on the growth mechanism have thus been associated with different scenarios describing the possible mechanisms of brookite crystal growth [13,17,[20][21][22]. Indeed, the use of a water-based growth environment has been a common denominator for most of the reported work on the growth of brookite nanostructures.…”

“…There have been many reported techniques for the synthesis of brookite nanostructures in an aqueous environment [12][13][14][15][16][17][18][19][20][21][22][23], most of which require very long growth times and several steps during the growth process. Furthermore, some of the previously reported techniques result in multiphase nanostructures with mixed brookite/anatase or brookite/rutile TiO 2 phases, where a high control over the phase ratios and resulting morphologies is yet to be achieved [13,[16][17][18][19]. Water-soluble complexes are usually used as titanium precursors, and the effect of growth parameters such as pH, temperature and complex ligands have been well addressed in the literature [12,18,20].…”