Nanoscale corrosion analysis via in-situ surface potential mapping: Enhancing electrochemical insight with OL-EPM and AC-KPFM

Local nanoscale mapping of electrical surface potential (ESP) is advancing rapidly to meet the needs of electrochemistry and corrosion science. Conventional Kelvin probe force microscopy (KPFM), while valuable, is limited in liquid and dynamic redox environments due to restricted electrochemical control and spatial resolution. Recent advances in alternating current KPFM (AC-KPFM) and open-loop electric potential microscopy (OL-EPM) provide high-resolution, in-situ ESP imaging while suppressing parasitic Faradaic reactions. AC-KPFM is powerful for probing ionization and counterion interactions at solid–liquid interfaces, whereas OL-EPM enables visualization of corrosion initiation, nanoscale defects in coatings, and gradients across grain boundaries. Together, these methods bridge the gap between surface electrostatics and electrochemistry. Key challenges remain in temporal resolution, minimizing probe perturbations, and linking nanoscale data to macroscopic corrosion behavior. Nonetheless, these techniques reveal hidden electrochemical heterogeneities, clarify pathways of localized corrosion, and offer insights for designing durable, corrosion-resistant materials.