Selective Pd Deposition on Au Nanobipyramids and Pd Site-Dependent Plasmonic Photocatalytic Activity

The synthesis of anisotropic metal nanostructures is strongly desired for exploring plasmon-enabled applications. Herein, the preparation of anisotropic Au/SiO2 and Au/SiO2/Pd nanostructures is realized through selective silica coating on Au nanobipyramids. For silica coating at the ends of Au nanobipyramids, the amount of coated silica and the overall shape of the coated nanostructures exhibit a bell-shaped dependence on the cationic surfactant concentration. For both end and side silica coating on Au nanobipyramids, the size of the silica component can be varied by changing the silica precursor amount. Silica can also be selectively deposited on the corners or facets of Au nanocubes, suggesting the generality of this method. The blockage of the predeposited silica component on Au nanobipyramids enables further selective Pd deposition. Suzuki coupling reactions carried out with the different bimetallic nanostructures functioning as plasmonic photocatalysts indicate that the plasmonic photocatalytic activity is dependent on the site of Pd nanoparticles on Au nanobipyramids. Taken together, these results suggest that plasmonic hot spots play an important role in hot-electron-driven plasmonic photocatalysis. This study opens up a promising route to the construction of anisotropic bimetallic nanostructures as well as to the design of bimetallic plasmonic-catalytic nanostructures as efficient plasmonic photocatalysts.