Surfactant-Assisted Synthesis and Photocatalytic Activity of Anatase TiO₂ Nanocrystals

Anatase titanium oxide (titania, TiO₂ nanocrystals (NCs) with tailorable morphology and size were synthesized through a simple modified solvothermal approach, in which a trace amount of adscititious water was introduced into the nonaqueous system to act as hydrolysis agent to allow for the formation of uniform TiO₂ NCs. By precise choice of the molar ratios of the oleic acid (OAc) to alkylamines including oleylamine (OAm), hexadecylamine (HDA) and tri-n-octylamine (TOA), the morphology and size of the as-obtained TiO₂ NCs could be manipulated easily due to the different binding energies of OAc and organic amines adsorbed on the different facets of TiO₂ NCs. Tetramethyl-ammonium hydroxide (TMAH) was used as the phase-transfer agent to make the different TiO₂ NCs disperse well in water. The photocatalytic performance of the as-obtained TiO₂ NCs with different morphology was evaluated by degradation of Rhodamine B (RhB) and hydrogen production under UV light. The results indicated that the photocatalytic activity was in close association with the exposed facets, and the synergy of high-energy {001} and {100} facets and low-energy {101} facets contributed to the improved photocatalytic performance.