Effect of Trimethylamine on the Formation
of Anatase Titania Nanoparticles by GelSol Method¹

X. P. Zhou^a, Z. F. Peng^b, Z. Q. Wang^a, and X. Q. Wang^c

^a Institute of Biological Sciences and Biotechnology, Donghua University,
North Remin Road 2999, Shanghai, 201620 P.R. China

^b College of Life and Environmental Science, Shanghai Normal University,
Shanghai 200 234, P.R. China

^c College of Material Science and Engineering, Donghua University, Shanghai, 201620 P.R. China

e-mail: xpzhou@dhu.edu.cn

Received March 23, 2007

Abstract—The anatase titania particles with controlled size and shape were prepared in large amount in the
presence of trimethylamine (TMA) from the hydrolysis of a Titriethanolamine (TEOA) complex by gelsol
method. In the absence of TMA, ellipsoidal particles were obtained due to the anisotropic growth caused by the
specific adsorption of TEOA onto the crystal planes parallel to the c-axis of a titania particle. TMA acted as a
complexing agent of Ti(IV) ion to promote the growth of ellipsoidal particles and then inhibited the anisotropic
crystal growth to produce ellipsoids of a low aspect ratio, rather than a shape controller to produce ellipsoids
with a high aspect ratio. This may be explained in terms of the weak complexing between TMA (a tertiary
amine) and Ti(IV) ion. The particle size was also controlled by seeding of anatase titania. Moreover, the seeding
suggested that the rate-determining step of the gelsol process was not the dissolution of the hydroxide gel, but
the deposition of the monomeric precursor from the solution phase. Some cationic surfactants also promoted
the particle grown to produce particles with a high symmetry in a similar way to TMA.

DOI: 10.1134/S1061933X08010055

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