Tunable Plasmonic Nanoparticles: from Single Nanoparticle SERS to Nanocatalysis

Nicolas Large Department of Chemistry, Northwestern University, Evanston, Illinois, USA Hao Jing Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA Qingfeng Zhang Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA Peter Nordlander Department of Physics and Astronomy, Rice University, Houston, Texas, USA Hui Wang Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA

Noble metal nanoparticles have been of tremendous interest due to their intriguing size- and shape-dependent plasmonic and catalytic properties. In particular, single-particle surface-enhanced Raman spectroscopy (spSERS) under near-infrared excitation has attracted special attention for a large range of bio-medical applications, drug detection, and many others application. Here, we report on the fabrication and characterization of Au nanoparticles (AuNPs) that possess size-dependent tunable plasmon resonances and intense near-field enhancements exploitable for spSERS: tipped AuNPs[1] and porous AuNPs[2] (Figure, A). Combining tunable plasmon resonances[1-2] with superior catalytic activities[3] on the same metallic nanoparticle, however, has long been challenging because nanoplasmonics and nanocatalysis typically require nanoparticles in two drastically different size regimes. Here, we also show that the creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Using site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, we have controllably fabricated nanorice and nanodumbbell particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high-index facets abundant on the particle surfaces (Figure, B). The nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time-resolved plasmon-enhanced spectroscopic measurements.

Figure: (A) Tipped AuNPs for spSERS: trisoctahedron, concaved nanocube, nanostar, and porous AuNPs. (B) Etching pattern of the nanocuboids: nanodumbell and nanorice.

References:

[1] Q. Zhang, N. Large, H. Wang, Gold Nanoparticles with Tipped Surface Structures as Substrates for Single-Particle Surface-Enhanced Raman Spectroscopy: Concave Nanocubes, Nanotrisoctahedra, and Nanostars, ACS Appl. Mater. Interfaces 6, 17255 (2014)

[2] Q. Zhang, N. Large, P. Nordlander, H. Wang, Porous Au Nanoparticles with Tunable Plasmon Resonances and Intense Field Enhancements for Single-Particle SERS, J. Phys. Chem. Lett. 5, 370 (2014)

[3] H. Jing, N. Large, P. Nordlander, H. Wang, Epitaxial Growth of Cu2O on Ag Allows for Fine Control Over Particle Geometries and Optical Properties of Ag-Cu2O Core-Shell Nanoparticles, J. Phys. Chem. C 118, 19948 (2014)

[4] H. Jing, Q. Zhang, N. Large, C. Yu, D.A. Blom, P. Nordlander, H. Wang, Tunable Plasmonic Nanoparticles with Catalytically Active High-Index Facets, Nano Lett. 14, 3674 (2014)

Nicolas.Large@northwestern.edu









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