Low-temperature synthesis of nanocrystalline TiO2 anatase is a very big problem when using sputtering technology, CVD and other methods. For getting crystalline anatase temperature used in these synthesis methods is usually around 300°C and higher. But researchers at Vietnam have synthesised nanocrystalline TiO2 at a low-temperature of 60°C by sol-gel technique with glass and Nafion substrates to get nanocrystallline .

Titanium tetraisopropoxide (TTIP) (98%), ethanol (99.5%), HCl (37%), water and PEG 600 were used by them as the starting materials. Water and 3% of PEG 600 (av. mol wt 600) were then introduced to the mixture with vigorous stirring at 80°C to allow the formation of a stable, homogenous and transparent sol solution. Following the process, titania sol formed by this procedure was deposited on the substrates of glass and Nafion N117 membrane by spin coating. The substrates coated by titania sol were taken out and dried at 60°C in a vacuum dryer for 8 hours. PEG aided sol-gel process produced a very stable colloidal solution. The water added together with PEG in the hydrolysis mixture has some molecules associated with the PEG through hydrogen bonding. The sol particles formed by the sol-gel reaction are covered by the PEG chains to form particle-PEG complex and physical cross-linking and agglomeration of these particulate complexes leads to an inorganic polymer composite. The thin solid film of TiO2 on Nafion membrane prepared by sol-gel was identified to be single anatase phase of nanosize TiO2 particles, it is dense and appears to be well attached to the membrane.