If you are in aqueous solution, the TiCl4 will hydrolyse- forming TiO2 in solution, this would make the colour of the solution change from transparent to milky/white due to TiO2 nanoparticles being suspended. So yes, a colour change is expected!

I agree with Prof. Michael John, the color changing is expected during the synthesis of TiO2 particles especially after calcination (200 to 400°C). I used TiCl4 to prepare TiO2–montmorillonite composie

( please find the attached files ).

Regards

Ridha

Dear Dr Michael,

Thanks for your reply.

I agree with your opinion, but the hydrolysis product is titanium hydroxide.

I'm not sure that the occurrence of hydrolysis is OK or not in preparation of TiO2 seed layer on the FTO substrate?

Though it will convert to TiO2 with following calcination.

Dear Dr Ridha,

Thanks for your reply and your interesting papers.