Precise Probing of Interfaces at the Single-Molecule Scale

The macroscopic functionality of nanoscale systems is fundamentally governed by microscopic physicochemical processes at material interfaces. However, conventional ensemble-averaged characterization techniques often obscure these subtle interfacial nuances due to their inherent limitations in spatial and temporal resolution. This review examines how single-molecule electrical measurements overcome these constraints by acting as precise analytical probes that directly transduce interfacial events into quantifiable conductance signals. By summarizing recent advances, we demonstrate how this approach resolves key physical interfacial characteristics, including distinct bonding motifs, steric configurations, and electronic coupling. We further summarize the real-time chemical interrogation of solid-liquid boundaries, which enables the capture of covalent bond formation kinetics, the dissection of catalytic reaction mechanisms, and the tracking of dynamic ion adsorption and proton transfer. Collectively, these investigations reveal interfaces as active, dynamically responsive physicochemical environments rather than simple passive structural boundaries. Finally, we propose that when employed primarily as high-resolution diagnostic tools rather than standalone electronic components, single-molecule junctions bridge atomic-scale interfacial mechanisms with macroscopic material performance, thereby providing an essential mechanistic foundations for the rational design of functional nanointerfaces.