Nanopipette‐based electrochemical SERS platforms: Using electrodeposition to produce versatile and adaptable plasmonic substrates

A method for fabricating localized EC-SERS probes based on nanopipettes and electrodeposition is described. Gold particles of fractal geometry with excellent SERS performance are produced, reliably and at low cost. By adapting the electrodeposition procedure, nanostructures of different sizes can be obtained, allowing the SERS platform to be tailored to many experimental configurations. In particular, by producing unique SERS platforms of dimensions comparable to the laser spot, quantitative comparison with electrochemical current is possible. By analyzing hundreds of samples, we thoroughly characterize the resulting geometry of the structures and their ability to enhance Raman signal, providing guidelines for the fabrication of optimized platforms. Control over the probes' surface potential also allows convenient modulation of surface-analyte affinity and enable chemically unstable materials, such as Cu, to be reliably used. These are demonstrated by showing that Cu particles exposed to air can be easily re-reduced, with no detriment in SERS performance.