Cross-Validation of Electrochemical, Spectroscopic, and Gravimetric Methods for Characterizing Self-Assembled Monolayers

Self-assembled monolayers (SAMs) are widely used to tune the properties of metal electrode surfaces, with applications ranging from sensing to electrocatalysis. However, the structure, coverage, and stability of SAMs often evolve under applied potential, and no single experimental technique provides a complete description of these changes. This work demonstrates the application of several surface characterization techniques, including voltammetric, spectroscopic, and gravimetric methods, on a model SAM system comprised of 4-mercaptobenzonitrile (4-MBN) on a gold electrode. We evaluate and cross-validate these complementary techniques, discussing their ability to support inferences about dynamic surface behavior. These analyses provide information regarding molecular identity, relative orientation, surface accessibility, and adsorbate coverage; specific to the 4-MBN SAM we report for the first time the adsorption isotherm and kinetic parameters for adsorption. This study demonstrates a characterization framework to investigate SAM dynamics and aims to support contemporary in situ SAM studies within the electrochemistry and surface science communities.