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Galvanic synthesis of three-dimensional and hollow metallic nanostructures.

Park SH, Son JG, Lee TG, Kim J, Han SY, Park HM, Song JY - Nanoscale Res Lett (2014)

Bottom Line: Finally, the wet etching process of remaining silver resulted in the formation of 3D-NPG.During the GRR process, the application of bias voltage to the cathode decreased the porosity of 3D-NPG in the voltage range of 0.2 to -0.62 V.The 3D-NPG nanostructures were found to effectively enhance the SERS sensitivity of rhodamine 6G (R6G) molecules with a concentration up to 10(-8) M.

View Article: PubMed Central - PubMed

Affiliation: Korea Research Institute of Standard and Science, Daejeon, 305-340, Republic of Korea, psh@kriss.re.kr.

ABSTRACT
We report a low-cost, facile, and template-free electrochemical method of synthesizing three-dimensional (3D) hollow metallic nanostructures. The 3D nanoporous gold (3D-NPG) nanostructures were synthesized by a galvanic replacement reaction (GRR) using the different reduction potentials of silver and gold; hemispherical silver nanoislands were electrochemically deposited on cathodic substrates by a reverse-pulse potentiodynamic method without templates and then nanoporous gold layer replicated the shape of silver islands during the GRR process in an ultra-dilute electrolyte of gold(III) chloride trihydrate. Finally, the wet etching process of remaining silver resulted in the formation of 3D-NPG. During the GRR process, the application of bias voltage to the cathode decreased the porosity of 3D-NPG in the voltage range of 0.2 to -0.62 V. And the GRR process of silver nanoislands was also applicable to fabrication of the 3D hollow nanostructures of platinum and palladium. The 3D-NPG nanostructures were found to effectively enhance the SERS sensitivity of rhodamine 6G (R6G) molecules with a concentration up to 10(-8) M.

No MeSH data available.


Schematic diagram depicting the three fabrication steps of 3D-NPG nanostructures. (a) Hemispherical silver nanoislands, (b) core-shell nanostructures after GRR, and (c) 3D-NPG nanostructures after a selective etching of silver.
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Fig1: Schematic diagram depicting the three fabrication steps of 3D-NPG nanostructures. (a) Hemispherical silver nanoislands, (b) core-shell nanostructures after GRR, and (c) 3D-NPG nanostructures after a selective etching of silver.

Mentions: Figure 1 shows a schematic diagram that the 3D-NPG ultra-thin nanostructures were formed by the GRR and selective etching processes. First, hemispherical silver nanoislands are electrodeposited on a cathodic Au substrate without any templates or surfactants, as reported in a previous study (Figure 1a) [26]. Secondly, the silver atoms on the nanostructure surface are replaced by gold atoms, according to the GRR process, when the nanostructure is immersed in a 50 μM HAuCl4 · nH2O aqueous solution without any external voltages, as shown in Figure 1b. The 3D-NPG nanostructures are formed by replicating the silver nanoislands, after a selective etching of the silver cores (Figure 1c).Figure 1


Galvanic synthesis of three-dimensional and hollow metallic nanostructures.

Park SH, Son JG, Lee TG, Kim J, Han SY, Park HM, Song JY - Nanoscale Res Lett (2014)

Schematic diagram depicting the three fabrication steps of 3D-NPG nanostructures. (a) Hemispherical silver nanoislands, (b) core-shell nanostructures after GRR, and (c) 3D-NPG nanostructures after a selective etching of silver.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493846&req=5

Fig1: Schematic diagram depicting the three fabrication steps of 3D-NPG nanostructures. (a) Hemispherical silver nanoislands, (b) core-shell nanostructures after GRR, and (c) 3D-NPG nanostructures after a selective etching of silver.
Mentions: Figure 1 shows a schematic diagram that the 3D-NPG ultra-thin nanostructures were formed by the GRR and selective etching processes. First, hemispherical silver nanoislands are electrodeposited on a cathodic Au substrate without any templates or surfactants, as reported in a previous study (Figure 1a) [26]. Secondly, the silver atoms on the nanostructure surface are replaced by gold atoms, according to the GRR process, when the nanostructure is immersed in a 50 μM HAuCl4 · nH2O aqueous solution without any external voltages, as shown in Figure 1b. The 3D-NPG nanostructures are formed by replicating the silver nanoislands, after a selective etching of the silver cores (Figure 1c).Figure 1

Bottom Line: Finally, the wet etching process of remaining silver resulted in the formation of 3D-NPG.During the GRR process, the application of bias voltage to the cathode decreased the porosity of 3D-NPG in the voltage range of 0.2 to -0.62 V.The 3D-NPG nanostructures were found to effectively enhance the SERS sensitivity of rhodamine 6G (R6G) molecules with a concentration up to 10(-8) M.

View Article: PubMed Central - PubMed

Affiliation: Korea Research Institute of Standard and Science, Daejeon, 305-340, Republic of Korea, psh@kriss.re.kr.

ABSTRACT
We report a low-cost, facile, and template-free electrochemical method of synthesizing three-dimensional (3D) hollow metallic nanostructures. The 3D nanoporous gold (3D-NPG) nanostructures were synthesized by a galvanic replacement reaction (GRR) using the different reduction potentials of silver and gold; hemispherical silver nanoislands were electrochemically deposited on cathodic substrates by a reverse-pulse potentiodynamic method without templates and then nanoporous gold layer replicated the shape of silver islands during the GRR process in an ultra-dilute electrolyte of gold(III) chloride trihydrate. Finally, the wet etching process of remaining silver resulted in the formation of 3D-NPG. During the GRR process, the application of bias voltage to the cathode decreased the porosity of 3D-NPG in the voltage range of 0.2 to -0.62 V. And the GRR process of silver nanoislands was also applicable to fabrication of the 3D hollow nanostructures of platinum and palladium. The 3D-NPG nanostructures were found to effectively enhance the SERS sensitivity of rhodamine 6G (R6G) molecules with a concentration up to 10(-8) M.

No MeSH data available.