For the synthesis of pure TiO2 by sol–gel technique, titanium
isopropoxide (Sigma–Aldrich) was taken as one of the precursor
solution and a mixture of distilled water with 2-propanol was the
other precursor solution. The synthesis process was started by the
mixing 250 mL of double distilled water with 15 mL of 2-propanol.
The pH of this first precursor solution was adjusted to 2 using nitric
acid [13]. A 5 mL titanium isopropoxide was taken as the second
precursor solution. The titanium precursor was added drop wise
into the first precursor under vigorous stirring in room temperature
with equal interval of time. A white drop like precipitate was the
immediate response from the solution. After completing the drop
wise addition of titanium precursor, the precipitation was allowed
to settle down under a temperature of 60 ◦C for half an hour. The
white precipitation was washed severaltimes in distilled water and
then in methanol to remove the impurities. The precipitation was
dried and fine white powder of TiO2 was harvested.