Preparation and Characterization of H_2Ti_4O_9 Nanocrystals

H_2Ti_4O_9 nanocrystals with high specific surface areas were prepared by delamination and precip- itation process through ball milling combined with ion exchange reaction.The samples were characterized by X-ray powder diffraction,transmission electron microscope,thermal analysis,N_2 adsorption-desorption isotherm, and absorption spectrum.The crystallites of Ti_4O_9~(2-) in the form of titania nanosheets have lateral size less than 50nm.The specific surface area of H_2Ti_4O_9 nanocrystals depends on pH values of precipitation solution and ball milling time.The specific surface area of H_2Ti_4O_9 nanocrystals prepared by ball-milling of K_2Ti_4O_9 for 2h and suspending in 1mol/L HCl followed by precipitation at pH=8 can reach 328.4m~2·g~(-1).