Fabrication of a Vertically Aligned Au Nanorod Array via Block‐Copolymer‐Templated Electroplating

Abstract

Hexagonally assembled gold (Au) nanorod arrays oriented perpendicular to the substrate are fabricated by block‐copolymer‐templated electroplating. An amphiphilic diblock copolymer consisting of poly(ethylene oxide) (PEO) and poly(methacrylate) bearing an azobenzene mesogen on the side chain (PEO‐b‐PMA(Az)) thin film is used as a template without any nanopore‐generation processes. The PEO within the microphase‐separated cylindrical domains of the template function as an electrolytic medium to electroplate Au. The Au nanorods selectively grow through the PEO cylindrical domains. The growth process of the Au nanorods is monitored using cyclic voltammetry and field emission scanning electron microscopy. The feature size (diameter, periodicity, and length) of the Au nanorods is controlled by the feature size and thickness of the template and the amount of passed charge. The optical characteristics of the resulting Au nanorod array are carefully investigated, including angle‐dependent ultraviolet–visible–near infrared spectra and surface enhanced Raman scattering activity. In addition, the morphology of Au nanorods in the template change into Au nanoparticles based on Rayleigh instability.

Highly Uniform Fabrication of Gold Nanoparticles on Carbon Nanotube Sheets for Sensors Based on Surface-Enhanced Raman Spectroscopy with Improved Reproducibility

“…Such a reshaping effect from DMSO on Au and Ag particles has been reported by other researchers too. , It has been demonstrated that DMSO binds gold atoms in a preferential way . For instance, it has been reported that both O and S from DMSO could coordinate with the surface of Au nanocrystals, which stabilizes Au {311} facets and creates Au NPs in the trapezohedral shape . In our work, it is likely due to the strong binding energy between S and Au, which promotes the nucleation of Au clusters on spots surrounding the S element, as shown in Figure c.…”

“…35 For instance, it has been reported that both O and S from DMSO could coordinate with the surface of Au nanocrystals, which stabilizes Au {311} facets and creates Au NPs in the trapezohedral shape. 34 In our work, it is likely due to the strong binding energy between S and Au, 36 which promotes the nucleation of Au clusters on spots surrounding the S element, as shown in Figure 5c. The deposition of Au atoms continues from the core and gradually spherical nanoparticles are formed.…”

“…Such a reshaping effect from DMSO on Au and Ag particles has been reported by other researchers too. 33,34 It has been demonstrated that DMSO binds gold atoms in a preferential way. 35 For instance, it has been reported that both O and S from DMSO could coordinate with the surface of Au nanocrystals, which stabilizes Au {311} facets and creates Au NPs in the trapezohedral shape.…”

Terahertz emission from gold nanorods irradiated by ultrashort laser pulses of different wavelengths

“…The Au nanorod sample was fabricated on a Au-coated glass substrate by electroplating with use of a liquid crystalline block copolymer template PEO- b -PMA(Az), which is consisted of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(methacrylate) bearing an azobenzene mesogen on the side chain (PMA(Az)) 15,16 . The thickness of the Au coating was around 15 nm.…”

Seed-Mediated Electroless Deposition of Gold Nanoparticles for Highly Uniform and Efficient SERS Enhancement

“…In contrast to other coating techniques, such as sputtering, chemical vapor deposition (CVD), ion beam assisted deposition, pulsed vacuum arc deposition (PVAD) [ 12 , 13 , 14 ], electroplating, electrochemical or electrophoresis deposition [ 15 , 16 ], EP required neither complicated, expensive equipment nor sophisticated operation. This method has been developed to fabricate large-area, uniform and reproducible substrates for surface-enhanced Raman scattering (SERS) [ 17 , 18 , 19 , 20 ].…”