Guided Assembly of Two-Dimensional Arrays of Gold Nanoparticles on a Polycrystalline Gold Electrode for Electrochemical Surface Enhanced Raman Spectroscopy

摘要

Development of a reproducible two-dimensional array of gold nanoparticles (AuNPs) through a guided assembly approach and sequentially using an electrochemical cleaning procedure to remove all capping ligands and surface contaminants for studying gluconate, a weak Raman scatterer, with electrochemical surface-enhanced Raman spectroscopy (SERS) is discussed. Here, a unique use of shell-isolated nanoparticles (NPs) is presented by employing a thin-cell configuration during NP deposition to obtain a highly reproducible monolayer of AuNPs with spacing by 2X the SiO2 shell thickness. Upon SiO2 dissolution and electrochemical cleaning, a well-ordered arrangement of bare AuNPs was achieved. The SERS active electrode modified with NP arrays was used for the characterization of gluconate adsorption. Enhanced spot-to-spot reproducibility of the SERS signal was achieved, allowing for significant reduction in the acquisition time needed for recording SERS spectra and investigation of gluconate adsorption on gold surfaces at short times. The results collected suggest that gluconate has undergone some electrooxidation but remains well-hydrated in the interfacial region.