Shape Transformation of Gold Nanoplates and their Surface Plasmon Characterization: Triangular to Hexagonal Nanoplates

Hong, Soonchang,Shuford, Kevin L.,Park, Sungho American Chemical Society 2011 Chemistry of materials Vol.23 No.8

<P>We present a simple synthetic method for hexagonal Au nanoplates. Selective etching of specific facets of triangular nanoplates has led to the shape transformation. Also, the high quality of hexagonal Au nanoplates allows one to identify the higher-order plasmon resonance bands in addition to the dipole mode.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2011/cmatex.2011.23.issue-8/cm103273c/production/images/medium/cm-2010-03273c_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm103273c'>ACS Electronic Supporting Info</A></P>

High-Yield Synthesis of Single-Crystalline Gold Nano-octahedra

Li, Cuncheng,Shuford, Kevin ,L.,Park, Q.-Han,Cai, Weiping,Li, Yue,Lee, Eun ,Je,Cho, Sung ,Oh WILEY-VCH Verlag 2007 Angewandte Chemie Vol.46 No.18

<B>Graphic Abstract</B> <P>Pieces of eight: Single-crystalline Au nano-octahedra with well-defined shape and tunable size can be synthesized by a modified polyol process. The octahedral Au nanocrystals have sharp corners and display optical properties that are sensitive to the crystal sizes and the truncation of the tips. <img src='wiley_img/14337851-2007-46-18-ANIE200604167-content.gif' alt='wiley_img/14337851-2007-46-18-ANIE200604167-content'> </P>

Observation of a quadrupole surface plasmon mode for Au nanorods: effects of surface roughness and crystal facets.

Hong, Soonchang,Shuford, Kevin L,Park, Sungho Wiley-VCH 2013 Chemistry, an Asian journal Vol.8 No.6

<P>This paper describes how the surface roughness and synthetic methods of Au nanorods affect the optical properties that are often associated with localized surface plasmon resonances. We synthesized Au nanorods with different aspect ratios and surface roughness by using two different synthetic strategies to observe surface plasmon resonance bands. One set of nanorods was prepared in high yield by using a seed-mediated dropwise-addition method with a growth-directing surfactant in aqueous solution (Au nanorods in aqueous phase, GNRA). The other set of Au nanorods were synthesized by the electrochemical deposition of Au onto an anodized aluminum oxide (AAO) template (Au nanorods by AAO template, GNRT). The length of the nanorods was controlled by changing the total charge that was passed through the cell and their diameter was monitored by changing the diameter of the template channel. The as-prepared Au nanorods were optimized to observe a quadrupole mode, which is one of the higher-order surface plasmon bands. Our results showed differences between the optical properties of GNRA and GNRT. The roughness and crystal structure of the Au nanorods affected their optical properties. Smooth and single-crystal surface on GNRA had larger and sharper peaks than GNRT. The discrete dipole approximation (DDA) method was used to calculate the optical properties of the Au nanorods and these results were in good agreement with our experimental results.</P>

Surface Plasmon Coupling on Linked Au–Pt Nanorods

Jung, Sujin,Liu, Lichun,Shuford, Kevin L.,Park, Sungho American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.6

<P>This work demonstrates that surface plasmon coupling in linked Au–Pt NRs (NRs) can be controlled by adjusting the relative ratio of material segment lengths. The NRs were synthesized through an anodic aluminum oxide template assisted sequential electrochemical deposition route. Optical spectra of the NRs in solution were acquired in the UV–vis–NIR region to examine surface plasmon coupling. Analysis of the spectra indicated that effective surface plasmon coupling could occur in Au-dominated NRs but not in Pt-dominated ones. The optical properties of Au–Pt–Au three-segment NRs were also examined, and the results provided further clarification regarding the conditions that yield effective coupling of NR segments in these structures. Electrodynamics calculations on two- and three-segment NRs were performed and found to be in good agreement with experiment. These findings regarding surface plasmon coupling of linked, hybrid NRs extend the fundamental knowledge of surface plasmon coupling from single component to hybrid systems and are useful for a variety of applications that necessitate fine controllability of the plasmonic properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-6/jp3114804/production/images/medium/jp-2012-114804_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3114804'>ACS Electronic Supporting Info</A></P>

Intra-particle Surface Plasmon Coupling in Nanorods

Sungwan Kim,Kevin L. Shuford,Hye-Mi Bok,Seong Kyu Kim,Sungho Park 한국진공학회 2008 한국진공학회 학술발표회초록집 Vol.2008 No.2

Intra-surface plasmon coupling between smooth and nanoporous blocks in a gold nanorod

Bok, Hye-Mi,Shuford, Kevin L.,Jeong, Eden,Park, Sungho Royal Society of Chemistry 2010 Chemical communications Vol.46 No.6

<P>We report an intraparticle surface plasmon coupling in Au nanorod structures consisting of half smooth and half nanoporous surface morphology; the relative ratio and the diameter difference between each block were important in determining the overall optical properties of such nanostructures.</P> <P>Graphic Abstract</P><P>We report an intraparticle surface plasmon coupling in Au nanorod structures consisting of half smooth and half nanoporous surface morphology. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b918510k'> </P>

Site-specific growth of a Pt shell on Au nanoplates: tailoring their surface plasmonic behavior.

Jang, Hee-Jeong,Hong, Soonchang,Ham, Songyi,Shuford, Kevin L,Park, Sungho RSC Pub 2014 Nanoscale Vol.6 No.13

<P>In this report, we tune the surface plasmonic behavior of Au nanoplates depending on the morphology of the Pt shell in which Pt is considered as a less optically inactive element. We describe the synthesis of flat Au nanoplates coated with Pt via rim-preferential or uniform growth methods. Depending on the site-selective growth of Pt on core Au nanoplates, the aspect ratio of the resulting Au@Pt nanoplates was tunable and their corresponding surface plasmon resonance (SPR) bands were controlled accordingly. Although Pt is regarded as an optically weak component in visible and near infrared spectral windows, a Pt coating affects the SPR behavior of core Au nanoplates due to effective surface plasmon (SP) coupling between the Au core and the deposited Pt shell. We systematically investigated the optical properties of uniformly grown (Au@Pt(uni)) and rim-preferentially grown (Au@Pt(rim)) Au@Pt nanoplates by observing their SPR band shifts compared to SPR of Au nanoplates. Due to the structural rigidity conferred by the Pt coating, the Au@Pt nanoplates can be easily transferred to the investigated solvents.</P>

Octahedral and Cubic Gold Nanoframes with Platinum Framework

Ham, Songyi,Jang, Hee‐,Jeong,Song, Yookyung,Shuford, Kevin L.,Park, Sungho WILEY‐VCH Verlag 2015 Angewandte Chemie Vol.127 No.31

<P><B>Abstract</B></P><P>Herein, we report a general synthetic pathway to various shapes of three‐dimensional (3D) gold nanoframes (NFs) embedded with a Pt skeleton for structural rigidity. The synthetic route comprises three steps: site‐specific (edge and vertex) deposition of Pt, etching of inner Au, and regrowth of Au on the Pt framework. Site‐specific reduction of Pt on Au nanoparticles (NPs) led to the high‐quality of 3D Au NFs with good structural rigidity, which allowed the detailed characterization of the corresponding 3D metal NFs. The synthetic method described here will open new avenues toward many new kinds of 3D metal NFs.</P>

Fabrication of 2D Au Nanorings with Pt Framework

Jang, Hee-Jeong,Ham, Songyi,Acapulco, Jesus A. I.,Song, Yookyung,Hong, Soonchang,Shuford, Kevin L.,Park, Sungho American Chemical Society 2014 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.136 No.50

<P>Surface plasmonics of nanomaterials has been one of the main research themes in nanoscience. Spherical and elongated nanoparticles show their corresponding unique optical features mainly depending on the physical dimensions. Here we successfully synthesized Au nanorings having Pt framework (Pt@Au nanorings) with high uniformity through wet-chemistry. The synthetic strategy consisted of serial reactions involving site-selective growth of Pt on the rim of Au nanoplates, subsequent etching of Au nanoplates, followed by regrowth of Au on the Pt rim. In this synthetic method, Au<SUP>3+</SUP> ions exhibited dual functionality as an etchant and a metal precursor. The resultant product, Pt@Au nanorings, exhibited unique localized surface plasmon resonance (LSPR) bands originating from the Au shell. The inner Pt skeleton turns out to be important to hold structural stability.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2014/jacsat.2014.136.issue-50/ja510916y/production/images/medium/ja-2014-10916y_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja510916y'>ACS Electronic Supporting Info</A></P>

Asymmetric Ag Nanocrescents with Pt Rims: Wet-Chemical Synthesis and Optical Characterization

Jang, Hee-Jeong,Jung, Insub,Zhang, Liqiu,Yoo, Sungjae,Lee, Sangji,Cho, Sanghyun,Shuford, Kevin L.,Park, Sungho American Chemical Society 2017 Chemistry of materials Vol.29 No.12

<P>A rational and controllable synthetic method for asymmetric nanoparticles in the solution phase is very rare and remains a major challenge. Among pseudo-two-dimensional nano particles, plasmonically active asymmetric nanocrescents have been intensively investigated because of their unique strong near-field enhancement and light confinement at the tips. Herein, we demonstrate the synthesis of highly uniform Ag-dominant nano crescents with Pt rims (AgPtrim, NCs) in an aqueous medium, by adopting Pt split rings as a scaffold for asymmetric growth. The asymmetric nanocrescents collectively exhibited characteristic localized surface plasmon resonance bands, including in-plane and out-of-plane modes, which matched the calculated spectrum of a single Ag nanocrescent, demonstrating the high level of uniformity of the synthesized nanocrescents. We observed light confinement and field enhancement at the sharp tips of the AgPtrim, NCs by comparing their Raman intensity with that from their analogous nano disks.</P>