I am Working on Tio2 photocatalyst behavior,I would be glad if anyone has could answer my questions???

1- is there any where which i could get Tio2 colloidal dispersion in water?

how much should be the percent of Tio2 in that colloidal dispersion that could provide me photocatalyst behavior?

2-if i want to make this colloidal dispersion from availabe precursors how should i start?Can you suggest a method?

Thanks in Advance