Preparation of SERS-active electrodes via ex situ electrocrystallization of silver in a halide free electrolyte

A roughening procedure for electrodes, on which afterwards intense SERS spectra of adsorbed molecules can be measured, is described. The desired roughness is obtained ex situ from a halide free electrolyte solution, through the electrodeposition of silver in a potentiostatic double potential step. The reproducibility of SERS spectra obtained on these deposits is limited due to different particle size distributions. It is explained that this is inevitable, due to the spatially random distribution of the silver crystals in combination with the overlap of the diffusion zones of the particles. Moreover, once a non-uniform particle size distribution exists, this can be amplified due to mass transfer limitations. The possibility to use these electrodes for quantitative SERS measurements, even when the intensity of the spectra between comparable experiments is different, is explored.