Morphology and photocatalytic performance of nano‐sized TiO 2 prepared by simple hydrothermal method with different pH values

Abstract pH value is a key factor in the preparation of nano‐sized TiO 2 with hydrothermal method. Using Ti(SO 4 ) 2 as the titanium source, H 2 O 2 as the complexing agent, NaOH and HCl as the pH value regulator, nano‐sized TiO 2 powder with various morphologies and sizes was synthesized. Changes in morphology, size and phase type with pH values of samples were characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. Results show that under the present preparation conditions, TiO 2 powder is an anatase phase with pH value less than 11, but is more likely to be a brookite phase with pH value more than 11. With the increase in pH value from 1 to 11 in hydrothermal environment, nano‐sized anatase TiO 2 gradually grows up in all directions. {001}, {101} and {100} groups of crystal plane are the exposed crystal planes of nano‐sized anatase TiO 2 for the (004), (101) and (200) facets found in high‐resolution TEM image. The photocatalytic performance of nano‐sized TiO 2 with different morphologies was compared by measuring their photocatalytic degradation rates for methylene blue under ultraviolet light. Results show that anatase TiO 2 prepared under the alkalescent hydrothermal environment (pH = 9, 11) has a better photocatalytic degrading performance. Different sizes and phases of nanoscaled TiO 2 powders with different photocatalytic performances can be prepared by the control of pH value of hydrothermal solutions.