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

Abstract

The synthesis of anisotropic metal nanostructures is strongly desired for exploring plasmon-enabled applications. Herein, the preparation of anisotropic Au/SiO 2 and Au/SiO 2 /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.

Silica‐Coated Plasmonic Metal Nanoparticles in Action

“…Another recent example of plasmon-enhanced photocatalysis was presented by Zhu et al, who investigated the activity of various anisotropic, bimetallic Au-Pd-nanostructures synthesized by site-selective silica protection of the gold cores. [58] As shown in Figure 16, higher conversion in a Suzuki coupling reaction could be achieved when the electric near-field was concentrated around the catalytically active sites, i.e. Pd.…”

“…[54] This can however be used as an advantage, as both site-selective vitreophilization of metal nanoparticles, and controlled shell porosity may lead to the construction of complex nanostructures such as Janus bimetallic heteroparticles, branched composites, or yolk-shell structures (Figure 1f). [14,[55][56][57][58][59] However, rather than increasing complexity, for many practical applications a seemingly trivial property of silica shells is a key advantage: robust and straightforward surface functionalization via silane coupling chemistry. Whereas hydrophobation is necessary for certain self-assembly approaches, [60,61] establishing long-lasting biocompatibility is crucial for the successful application of plasmonic particles in biotechnology.…”

“…It is worth noting that, as recently shown for gold nanobipyramids (AuNBPs) and gold nanocubes, the efficacy of curvature-induced site-selective silica coating strongly depends on the concentration of the stabilizing surfactant CTAB (Figure 5h-k). [58] Figure 5. Silica-templated synthesis of anisotropic, bimetallic heterostructures.…”

Rational selection of halide ions for synthesizing highly active Au@Pd nanobipyramids

“…[1][2][3][4][5][6][7][8][9][10] Their catalytic performance is highly dependent on composition, structure and shape.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Their catalytic performance is strongly dependent on the surface atoms, that is, the bounding facets. [10][11][12][13][14][15][16][17][18] Nanostructures with stepped facets exhibit relatively high activity, compared with commonly observed nanostructures.…”