Tipping Gold Nanobipyramids with Titania for the Use of Plasmonic Hotspots to Drive Amine Coupling

Designing plasmonic photocatalysts with spatially controlled catalytic sites is an effective strategy to boost the sunlight-driven chemical transformation efficiency through plasmonic enhancement. Herein, we describe a facile method for the synthesis of TiO₂-tipped Au nanobipyramids (NBPs) to give (Au NBP)/t-TiO₂ nanodumbbells. The surfactant cetyltrimethylammonium bromide concentration is the key factor in the construction of this type of unique nanostructure. The photocatalytic aerobic oxidative coupling of amines using the plasmonic photocatalysts with the dumbbell-like and core@shell structures indicates that the TiO₂-tipped ends for the photo-reduction and the exposed adjacent Au surface for the photo-oxidation on (Au NBP)/t-TiO₂ can significantly improve the photocatalytic activity. The underlying mechanism of the photocatalytic oxidative coupling of benzylamine over (Au NBP)/t-TiO₂ has been thoroughly investigated. Both experimental and simulation results for (Au NBP)/t-TiO₂ and (Au nanorod)/t-TiO₂ confirm the important effect of the plasmonic hotspots on the enhancement of the photocatalytic activity.