Atomic-Scale Insights into Copper Corrosion in Acidic Environment through Cryogenic Atom Probe Tomography of 3D-Electrodeposited Microcorrosion Cell

Abstract: Corrosion originates from atomistic reactions occurring at dynamic solid liquid interfaces; however, direct experimental observation of these reactions has remained elusive due to the inability to preserve transient interfacial states during characterization. To refine corrosion models, advanced techniques capable of analyzing corrosion interfaces at the atomic scale are essential. Recent advancements in cryogenic atom probe tomography (cryoAPT) enabled 3D nanoscale analysis of frozen liquid metal interfaces. However, challenges remain in sample preparation for cryoAPT on metals undergoing corrosion. This study introduces a microcorrosion cell fabricated using localized electrodeposition in liquid (LEL), enabling atomic scale capture of liquid metal reactions by integrating picoliter scale electrolytes encapsulated within sealed metallic microvessels, subsequently analyzed using cryoAPT. This approach enables 3D, nanoscale mapping of corrosion reactions with simultaneous spatial, chemical, and temporal resolution. As a model system, copper exposed to aerated dilute sulfuric acid reveals temperature and time dependent interfacial evolution, including nanoscale clustering of copper sulfate species, enhanced ion pairing at elevated temperature, and the emergence of transient carbon based interfacial complexes inaccessible to conventional characterization methods. Beyond copper corrosion, the presented microcorrosion cell architecture establishes a strategy for interrogating confined electrochemical and degradation processes across a wide range of material liquid systems, using a combination of microfabrication and cryoAPT.