Effects of Ag particle geometry on photocatalytic performance of Ag/TiO2 reduced graphene oxide ternary systems

TiO2 nanopowder (P25) is the commonly used commercial photocatalyst. However, because only a small ultraviolet portion of solar spectrum can excite the electron-hole pairs and their recombination rate is high, its efficiency is limited. In this study, we proposed silver nanostructures and reduced graphene oxide (RGO) to construct ternary plasmonic catalyst to improve the catalytic performance of TiO2. We prepared three different geometries of Ag nanostructures including sphere, decahedron and prism. While the incorporated Ag nanostructures led to an increase in light absorption due to localized surface plasmon resonance (LSPR), the RGO inhibited the charge recombination and enhanced the electron-hole separation. The finite-difference timedomain method was adopted to simulate the electric field intensity distributions in the three different geometries of Ag nanoparticles irradiated by the florescent lamp to verify the corresponding LSPR effects. Both Ag nanodecahedrons/P25/RGO and Ag nanoprisms/P25/RGO hybrid photocatalysts possessed remarkable photocatalytic activity, which decolorized the dyes up to 80% under white light irradiation for only 1 h and displayed over 8 times higher photocatalytic efficiency than P25 photocatalyst.