Graphene Wrapped TiO2 Based Catalysts with Enhanced Photocatalytic Activity----Technical Institute of Physics and Chemistry

Reduced graphene oxide (RGO) wrapped titanium dioxide nanocrystals (TiO₂ NCs@RGO) with oxygen vacancies (Vo) and Ti³⁺ defects have been synthesized by electrostatically wrapping GO around TiO₂ NCs followed by thermal annealing at 400 °C. Transmission electron microscope observations have shown that TiO₂NCs@RGO has a unique crystalline core/crystalline shell structure, which is different from the original amorphous TiO₂ covered TiO₂ NCs. Raman spectroscopy, X-ray photoelectron spectroscopy, and electron paramagnetic resonance have demonstrated that Vo-Ti³⁺ species are more readily formed in TiO₂ NCs@RGO than in TiO₂ NCs. As a result, TiO₂ NCs@RGO exhibits enhanced optical absorption in a wide wavelength range from visible light to near IR and red-shifted absorption edge. In the photocatalytic degradation reaction of methyl orange, the photodegradation rate constant for TiO₂ NCs@RGO is 2.4 times higher than that of TiO₂ NCs. The enhanced photocatalytic performance can be attributed to the improved charge separation at the interface of TiO₂ NCs and RGO layer and the enhanced optical absorption in visible light region due to the donor levels of the defects such as Vo-Ti³⁺ species. This work establishes a new method for preparing Vo defect contained TiO₂ catalysts.

Advanced Materials Interfaces