Single-molecule electrochemistry

Abstract Single-molecule electrochemistry (SME) is a subfield of electrochemistry with the goal of detecting, manipulating, and characterizing the faradaic response of individual redox molecules. The field of SME has received considerable attention since its first demonstration in the 1990s. This chapter summarizes various physical and analytical methods toward characterization of single molecules in electrochemistry. We introduce the concept of redox cycling and various experimental strategies of creating effective nanostructures to measure the faradaic signal of single redox molecules using redox cycling. We then describe the method of resistive-pulse sensing and discuss how a nanopore allows single biomolecules to be studied in great detail. In the second half of the chapter, we turn our attention to the use of optical microscopy to study electrochemical reactions of single redox molecules. Here, we concentrate on the uses of two main categories of optical methods: fluorescence microscopy and surface-enhanced Raman spectroscopy (SERS).