The high dispersion of Ti across the supports was confirmed by DRUV-vis (Fig. ) and XRD analyses. In Fig. (a), the band centered at ca. 215-245 nm is associated with ligand-to-metal charge transfer (LMCT) bands, that correspond to isolated tetrahedral TiO4 coordination, while the band in the 250-300 nm range can be attributed to the presence of Ti in higher coordination, such as water-coordinated Ti species, oligomeric or one-dimensional polymerized TiO4 and two-dimensional polymerized TiO5 . With an increase of Ti loading from 4% to 16%, the maximum absorption band shifts from 215 nm to 255 nm, suggesting larger amounts of Ti in higher coordination number than tetrahedral due to higher Ti polymerization. However, the characteristic band of octahedral TiO6 as in bulk TiO2 nanocrystals (i.e., anatase) at around 330 nm is never observed . Analysis of the band gap (Eg) also demonstrates that Ti atoms are mostly highly dispersed in the SiO2 matrix, even if a growing but minor fraction is present in the forms of oligomeric or small nanodomains of TiOx species when the Ti loading increases (see Supporting Information, Figure ). Consistent with the DR UV-vis results, the XRD patterns of all Ti-SiO2 materials (Fig. ) solely exhibit amorphous features without any TiO2 crystalline phase, albeit high Ti loading up to 16% .