In a typical synthesis, 5 g of TiCl4 (99%, Alfa Aesar) was
dissolved in 50 ml of ethanol (98%, Sinopharm. Co.) with con-tinuous stirring to form a transparent yellowish sol at 0
◦
Cin
an ice-water bath. After being stirred for 2 h, the transparent
sol was placed in an oven and baked at 80
◦
C for 3 days. The
obtained off-white powder was washed carefully using a cen-trifuge at a speed of 10,000 rpm to remove the organic species
and Cl
−
that were adsorbed onto the sample surfaces. The white
product thus obtained was dried at 50
◦
C in air. Samples of
50 mg were ultrasonically dispersed in 10 ml acidic water and
formed a stable colloidal suspension. The stabilities of these
colloids were investigated by adjusting the acidity of the mixed
solutions.