Track-Etched Membranes for Gold Nanowire SERS Substrates

Abstract

In this study, a novel and reliable method for the production of bimetallic Ni–Au segmented nanowires by template-assisted electrochemical deposition was developed. Track-etched membranes were used as templates for the synthesis of gold nanowires with a diameter of about 100 nm by electrochemical deposition. To enhance structural stability, a modified approach was proposed, wherein gold nanowires were grown on nickel nanowire cores instead of being deposited directly onto the copper layer, as is commonly practiced. The morphology and composition of the resulting nanostructures were characterized by scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDX). Elemental mapping analysis was performed to visualize the spatial distribution of constituent metals within the nanowires, revealing a well-defined segmented architecture: copper was localized at the base, nickel occupied the central region, and gold was selectively deposited on the top surface. The Surface-Enhanced Raman Scattering (SERS) activity of the substrates was evaluated using Rhodamine 6G at the concentration of 10–4 M, confirming their effectiveness for signal enhancement. The developed approach allows precise control of the nanostructures morphology and composition by separating the deposition stages for nickel and gold segments. By eliminating direct contact between gold and copper layers, this strategy effectively suppresses intermetallic diffusion, thereby enhancing the structural stability of the resulting bimetallic nanowires.