Surface Enhanced Raman Spectroscopy With Electrodeposited Copper Ultramicro-Wires With/Without Silver Nanostars Decoration

The electrochemical preparation of arrays of copper ultramicro-wires (CuUWs) by usingporous membranes as templates is critically revisited, with the goal of obtaining cheap but efficientsubstrates for surface enhanced Raman spectroscopy (SERS). The role of the materials used forthe electrodeposition is examined, comparing membranes of anodized aluminum oxide (AAO) vs.track-etched polycarbonate (PC) as well as copper vs. glassy carbon (GC) as electrode material.A voltammetric study performed on bare electrodes and potentiostatic tests on membrane coatedelectrodes allowed the optimization of the deposition parameters. The final arrays of CuUWswere obtained by chemical etching of the template, with NaOH for AAO and CH2Cl2for PC.After total etching of the template, SERS spectra were recorded on CuUWs using benzenthiol asSERS probe with known spectral features. The CuUW substrates displayed good SERS properties,providing enhancement factor in the 103–104range. Finally, it was demonstrated that higher Raman enhancement can be achieved when CuUWs are decorated with silver nanostars, supporting the formation of SERS active hot-spots at the bimetallic interface.