Cu-Pd Bimetal and CuPt Alloy Nanotubes Derived From Cu Nanowires: Novel Amplification Media for Surface-Enhanced Raman Spectroscopy

Surface-plasmons of metals have been utilized to enhance the Raman spectra of various adsorbed moieties for over decades. While amplification of the spectral intensity takes place on most of the metals, due to their superb properties, Au, Ag and Cu surfaces represent the benchmark in surface-enhanced Raman spectroscopy. In this paper, we show that Cu-Pd bimetal and CuPt alloy nanotubes derived from Cu nanowires by simple galvanic exchange reactions are suitable for the efficient enhancement of Raman spectra when dispersed on Si surfaces. Amplification factors of
$120\times $
on Cu nanowires,
$150\times $
on Cu-Pd bimetal nanotubes and
$250\times $
on CuPt alloy nanotubes in reference to the substrate are measured for rhodamine 6G and methyl violet model compounds. We also show that the nanotubes dispersed on Au surfaces can contribute to a further intensity enhancement of the substrate and detect analytes adsorbed from 10
⁻⁶
M analyte concentrations. Our results obtained using bimetallic and alloy nanomaterials shed light on a new strategy to synthetize and apply new types of metal nanostructures and compositions for surface-enhanced Raman spectroscopy in the future.