TiO2 NPs were prepared according to a reported method [30].
In a Schlenck tube, 0.5 mL of TiCl4 was mixed with 5 mL of 1-nbutyl-
3-methylimidazolium tetrafluoroborate ionic liquid under
argon atmosphere. The mixture was stirred hard for 10 min at room
temperature and 1 mL of deionized water was added slowly.