Facile Synthesis of TiO₂ with a Narrow Bandgap and Low Valence Band for Efficient Visible-Light Photocatalytic Degradation of Various Phenols

Abstract

Efficient, low-cost, and easily scalable wide-spectralresponsive TiO 2 photocatalysts are still extremely desired in driving photocatalytic degradation toward practical applications. In this work, a modified TiO 2 with a narrow band gap and low valence band (VB) (CC-OV-TiO 2 ) was successfully synthesized based on a facile sol−gel and lowtemperature carbonization process, which can be used for the photocatalytic degradation and mineralization of a wide range of phenols. The results show that the interstitial doping of carbonates and the modification of surface oxygen vacancy (OV) defects together contribute to the formation of the VB tail states, which substantially narrow the band gap of TiO 2 and widen the photoresponse range. Meanwhile, the carboxylated carbon species induce a substantial downward shift of the VB edge through coordination of the electron-withdrawing carboxyl groups, which further enhances the oxidation ability of the photogenerated holes. Accordingly, CC-OV-TiO 2 with a narrow band gap and low VB exhibits superior and stable photocatalytic performance.

Combined effect of Cu0 and oxygen vacancies in Cu-based zeolites enables highly efficient photo-Fenton-like performance for water purification

“…The VB tail would effectively reduce the energy required for the electronic transition, thereby enhancing the light absorption of the catalyst. 46,47 Conversely the E g of Cu 0 @CuZ-p was estimated to be 3.53 eV, which is much larger than that for Cu 0 @CuZ (Fig. S5†), resulting in an increase in the energy required to generate photogenerated electron–hole pairs by excitation in visible light.…”