Pinhole-Free Shell-Isolated Nanoparticle Enhanced Raman Spectroscopy for Interference-Free Probing of Electrochemical Reactions

Investigating the behavior of analytes at the electrode surface is crucial in understanding the electrochemical and electrocatalytic reactions. Although Surface Enhanced Raman Scattering (SERS) is sensitive to minor chemical changes in the analyte, it is not widely used to study the reaction mechanisms on nonplasmonic surfaces because of the interference from plasmonic SERS substrates. In this study, we have investigated the redox reaction of Nile Blue A on a glassy carbon surface using pinhole-free silica-coated silver nanoparticles for Raman signal enhancement. The silver nanostructures were synthesized by a chemical reduction method, and the quality of the silica layer was confirmed using microscopic and electrochemical method. The in situ spectroelectrochemical data reveals the catalytic interference from silver which considerably alters the native reaction mechanism. The pinhole-free silica layer prevents the hot electron transfer and yields an interference-free enhancement to the Raman signals.