Dependence of photocatalysis on electron trapping in Ag-doped flowerlike rutile-phase TiO2 film by facile hydrothermal method

Abstract

Ag-doped flowerlike rutile-phase (Ag-FR) TiO2 film with exposed (110) and (111) facet was fabricated by a facile hydrothermal method at 150 °C without additive or capping agent with different Ag content ranging from 0.5 to 2 wt%. This study investigated the influence of Ag content in enhancing the photocatalytic activity of Ag-FR TiO2 film. The flowerlike structures increased the active area of the TiO2 film. XPS revealed that the concentration of Ti3+-oxygen vacancy defects increased upon doping, while TEM revealed that the (110) and (111) are highly exposed facets of rods with flowerlike structure. The effectiveness of the Ag-FR TiO2 film was tested on methylene blue degradation under xenon lamp irradiation. The Ag-FR TiO2 film with 1 wt% Ag resulted in the highest methylene blue degradation, which was 20% higher than degradation by the undoped TiO2. The synergistic effect between both (110) and (111) facets and Ti3+-oxygen vacancy from Ag play an important role in reducing the band gap and acts as an electron trap. This suppresses recombination between electrons and holes to enhance the photocatalytic activity thus extending the lifetime of the photogenerated electron and hole.