Noble metal sandwich-like TiO 2 @Pt@C 3 N 4 hollow spheres enhance photocatalytic performance.

The goal of this work was to assess the performance of Pt nanoparticles (NPs) as co-catalysts on the photocatalytic activity of TiO2 @Pt@C3 N4 hollow spheres, which was tested by photodegrading rhodamine B and methyl blue under visible light irradiation. TiO2 @Pt@C3 N4 composites were fabricated by using modified polystyrene balls as templates, hydrothermal reactions, and calcination. Under simulated sunlight irradiation, photocatalytic activity was in the following of TiO2 @Pt@C3 N4  > TiO2 @C3 N4  > C3 N4  > P25. The photo-conversion rate of the TiO2 @Pt@C3 N4 increased significantly relative to TiO2 @C3 N4 and the others. The combination of TiO2 and C3 N4 , as well as the sandwiched of Pt NPs reduce electron-hole recombination as a result of having an electron trap site, which can store and shuttle photo-generated electrons, and enhance photo-generation of active radicals. Electron paramagnetic resonance (EPR) spectroscopy, as well as photo-luminescence (PL), and electrochemical measurements were taken to verify this conclusion. Considering the multi-functional combination of precious metals and semiconductor materials, this work may provide new ideas for the design of high-performance catalysts.