*2.2. Synthesis of TiO2 Nanoparticles*

TTIP (2% v-v) was added to a solution of HNO3 (1% v-v), CH3COOH (10% v-v), and distilled water (DW). The mixture was subjected to stirring for an extra 16 h at 60 ◦C. After cooling, TiO2 NPs were provided by continuously adding Na2CO3(aq) (5%) until reaching a full sedimentation of TiO2 NPs. The generated dispersion was centrifuged (4000 rpm) for 5 min, decanted, washed with DW, and dried at 100 ◦C over 3 h. The dispersion of the generated TiO2 NPs in DW was transparent and stable for several weeks at room temperature.
