**3. Conclusions**

**Figure 8.** (a) Rate capability and (b) specific discharge capacity comparison of CF-TiO<sup>2</sup>

charge/discharge and rate capabilities resulted from the higher specific surface area of the flakes which leads to faster transportation between Li-ion and electron within the matrix of titania lattice (**Figure 8a**). Besides, the porous morphology of the calcined flakes provided extra space for the volume change during cycling and therefore significantly improved the

**Figure 7.** Photocatalytic decomposition of methylene blue by using synthesized and calcined flakes (a) without bubbling

Using the same deposition method to assemble the DSSC, integrally and closely bonded films resulted from better particle dispersion of titania flakes (**Figure 9**). In contrast, discontinuity of P25 nanoparticle layers were observed after the evaporation and sintering processes [50]. Improved energy conversion efficiency of DSSC could be attributed to two features of titania flakes: (1) Stronger adsorption of visible dyes from high specific surface area (2) Micron scale in two dimensions lead to stronger light scattering of visible light spectrum. The important IV characteristics of DSSC such as short-circuit current density (Isc) and open-circuit voltage (Voc)

tions, calcined titania flakes demonstrated 5 times higher efficiency over the P25 photoelectrodes

nanoparticles.

cycling performance (**Figure 8b**).

treatment (b) with bubbling treatment.

50 Titanium Dioxide - Material for a Sustainable Environment

were found to be related to the thickness of the TiO<sup>2</sup>

under the same thickness basis (7.4% vs. 1.2%) (**Figure 10**).

(calcined nanoflakes) and TiO<sup>2</sup>

photoelectrodes. According to the calcula-

In summary, a high-aspect-ratio titania nanoflakes has been synthesized by the one-step modified surface hydrolysis. Compared to other methods for making low-dimensional nanomaterials, this spreading film process could continuously produce nanoflakes with a cost effective manner. These titania flakes could be easily separated from the treated water by simply sedimentation or filtration and therefore is very suitable for water purification application.

The major summary of applications were listed as follows: (1) Over 99% of methylene blue solution (50 μM) was degraded by the high aspect ratio calcined titania nanoflakes under UVA irradiation within 2 h, whereas not completely decomposition of dye solutions was achieved using P25 nanoparticles as photocatalysts under the same process condition. (2) Calcined nanoflakes exhibit larger reversible charge/discharge capacity, better rate capability and excellent cycling stability. (3) 7.4% of photon energy conversion efficiency of calcined flakes based DSSC which was 5 times improvement compared to P25 based cell was accomplished.

[9] Shen GZ, Bando Y, Liu BD, Golberg D, Lee C. Characterization and field-emission properties of vertically aligned ZnO nanonails and nanopencils fabricated by a modified

Novel Two-Dimensional Nanomaterial: High Aspect Ratio Titania Nanoflakes

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