Novel Two-Dimensional Nanomaterial: High Aspect Ratio Titania Nanoflakes

A novel 2D nanomaterial, high aspect ratio TiO 2 nanoflakes were synthesized by a one- step method. Surface morphology and physical dimensions were characterized using Scanning Electron Microscopy (SEM), Laser Diffraction technology, and Transmission Electron Microscopy (TEM). Micro-sized flakes having a thickness approximately 40 nm were successfully synthesized by spreading a mixture of titanium alkoxide and hydro- carbon on the water surface. Relatively higher specific surface area (2–6 times) and less crystal defects enhanced photocatalytic activities of nanoflakes due to more surface reac- tion sites. By performing dye degradation under ultraviolet (UV) illumination, titania nanoflakes exhibited the higher photocatalytic efficiency over the commercial photocata- lyst, Degussa P25. To the best of our knowledge, this is the first time to continuously synthesize low-dimensional nanomaterials in an efficient and cost effective manner. In practical water purification, traditional separation processes such as sedimentation or filtration could be utilized to easily extract the titania flakes from the treated water. Other applications such as anode material for lithium ion batteries and conducting paste in dye sensitized solar cells (DSSC) were also investigated. The cycling performance of Li-ion battery and energy conversion efficiency of DSSC were significantly improved. 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.