title: Facet Control of Gold Nanorods.
abstract: While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure-property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair of surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities.
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina , Columbia, South Carolina 29208, United States.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Lili
authors.initials: L
authors.lastname: Han
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina , Columbia, South Carolina 29208, United States.
authors.forename: Hao
authors.initials: H
authors.lastname: Jing
authors.affiliation: NanoCenter, University of South Carolina , Columbia, South Carolina 29208, United States.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Blom
authors.affiliation: Department of Chemical Engineering, University of South Carolina , Columbia, South Carolina 29208, United States.
authors.forename: Ye
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Huolin L
authors.initials: HL
authors.lastname: Xin
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina , Columbia, South Carolina 29208, United States.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
keywords: gold nanorods; high-index facets; low-index facets; nanocatalysis; overgrowth; plasmon resonances; surface-enhanced Raman spectroscopy