Double-layered nanoparticle stacks for spectro-electrochemical applications.

Here we present a surface based on double-layered nanoparticle stacks suitable for spectro-electrochemical applications. The structure is formed on a continuous gold layer by a two-dimensional periodic array of stacks of gold and tantalum pentoxide nanodisks. Reflection spectra in the visible wavelength region showed the multiple-resonant nature of surface plasmon (SP) excitations in the nanostructure, which is in good agreement with simulations based on a finite-difference-time-domain method. The multiple SP resonances can be tuned to various wavelength regions, which are required for simultaneous enhancement at excitation and emission wavelengths. Cyclic voltammetry measurements on the nanostructure proved the applicability of electrochemical methods involving interfacial redox processes.