International audienceWe demonstrate a facile fabrication of gold nanostructures including Au nanoplates (NPs), Au nanothorns (NTs), and Au nanowires (NWs) on indium tin oxide substrates via electrochemical growth. A simple two-electrode electrochemical deposition system was applied for the fabrication process. Dense Au nanostructures were grown directly on an Au seeding layer on the substrate. After 48 h, the Au NPs were 2−5 μm in width and 150−200 nm in thickness. The Au NTs were 1−3 μm in height, 300−500 nm in bottom side width, and 20 nm at the apex. The Au NWs were 30−80 nm in diameter and about 20 μm in length. The entire process was template-free and economical. We investigated the correlation between surface plasmon resonance (SPR) and surface enhanced scattering (SERS) effects of the Au nanostructures with different excitation wavelengths. By using the SPR absorption maxima of the nanostructures as the excitation wavelengths for SERS, the highest SERS enhancements were achieved. SERS effects of the Au NWs were investigated further. We discovered that the length and the density of the Au NWs affected the SERS performance significantly. The result is rationalized by the amount of "hot spot" generated at the crossing of the Au NWs. With the Au NWs, Rhodamine 6G can be detected at a concentration as low as 10−9 M
Urchin-like silver nanowires are prepared by reacting AgNO(3)(aq) with copper metal in the presence of cetyltrimethylammonium chloride and HNO(3)(aq) on a screen-printed carbon electrode at room temperature. The diameters of the nanowires are about 100 nm, and their lengths are up to 10 μm. Using Raman spectroscopy, the detection limit of Rhodamine 6G (R6G) on the urchin-like silver nanowire substrate can be as low as 10(-16) M, while the analytical enhancement factor is about 10(13). Raman mapping images confirm that a single R6G molecule on the substrate can be detected.
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