摘要
Visible-light-driven photocatalysis as a green technology has attracted a lot of attention due to its potential applications in environmental remediation. Although TiO 2 is the most popular photocatalyst, the lack of visible light utilization and a low efficiency of electron-hole separation should be overcome. Therefore, Au nanoparticles (NPs) as cocatalyst were controllably loaded between the double-shell or into CeO 2 shell (as photocatalyst and oxygen buffer) and then a novel visible-light-driven TiO 2 @CeO 2 nanocomposite was prepared, using functionalized polystyrene spheres, sol-gel, hydrothermal reaction, and calcination. The presence of TiO 2 shell, Au NPs and CeO 2 shell were confirmed by EDX and electron energy loss mapping analysis. Under visible-light irradiation, the photo-degradation rate constant k (min −1 ) was in the order of TiO 2 @Au@CeO 2 (0.026) > TiO 2 @CeO 2 /Au (0.021) > TiO 2 @CeO 2 (0.014) > CeO 2 (0.0091) > TiO 2 (0.0046) > P25 (0.0034). Compared with P25, TiO 2 @CeO 2 , and TiO 2 @CeO 2 /Au, the visible-light photocatalytic activity of TiO 2 @Au@CeO 2 for the photo-degradation of organic pollutant and photo-reduction of Cr(VI) were the highest. This result was attributed to the combination of TiO 2 and CeO 2 , the double-shelled and sandwiched nanostructure and the addition of Au NPs as electron trap site and surface plasmon resonance-sensitizer, which could reduce the recombination of the electron-hole and induce the visible light absorption. The major obstacle of heterogeneous photocatalysis could be resolved. The photo-degradation rate of 95% was achieved by TiO 2 @Au@CeO 2 , which exhibited an increase of 63% compared to Degussa P25 TiO 2 . The photo-degradation activity of TiO 2 @CeO 2 /Au was improved by Au NPs loaded on outer shell of TiO 2 @CeO 2 /Au but limited by their stability. This work confirmed the importance of controllable location of the noble metals as cocatalysts.
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