Plasmonic\nImaging of Surface Electrochemical Reactions\nof Single Gold Nanowires

Abstract

Nanomaterials have\nbeen widely used in energy and sensing applications\nbecause of their unique chemical and physical properties, especially\ntheir surface reactions. Measuring the local reactions of individual\nnanomaterials, however, has been an experimental challenge. Here we\nreport on plasmonic imaging of surface electrochemical reactions of\nindividual gold nanowires (AuNWs). We coated a gold thin film (plasmonic\nsensing layer) with a dielectric layer (Cytop) with refractive index\nclose to that of water, and then a graphene layer for electrical contact.\nThis design removed the interference from the sensing layer while\npreserving sharp surface plasmon resonance, which allowed us to obtain\ncyclic voltammograms of surface electrochemistry of individual AuNWs\nfor the first time. We also investigated the difference in the electrochemical\nreactions of AuNWs and Au surfaces, and local distribution of electrochemical\nactivities within a single AuNW.