To estimate the (band gap energy) of the studied samples the optical analysis was conducted. The DR-UV–Vis spectra of TiO2-Degussa P25, m-SiO2/TiO2,
The increase of the band gap of m-SiO2/TiO2 can be due to the fact that TiO2-Degussa P25 is composed of the anatase (~80% with band gap of ~3.2 eV) and rutile (~20% with band gap of ~3.0 eV)