Correlative Morphology-Mechanics Mapping Reveals Spatiotemporal Kinetics of Ag-Pt Galvanic Replacement

Galvanic replacement (GR) at solid-liquid interfaces enables nanoscale synthesis, yet its initiation and kinetics remain unclear. Here, scanning ion conductance microscopy enables noncontact, correlative mapping of morphology and apparent stiffness during Ag-Pt GR at single nanowires. We identify a mechanically defined initiation stage in which pronounced softening precedes detectable morphological change, establishing mechanical response as an early kinetic reporter. Quantitative extraction of effective mechanical rate constants provides a kinetic descriptor inaccessible to morphology alone. Stage-resolved maps further reveal nonmonotonic morphology-mechanics coupling and asynchronous activation of discrete surface sites that nevertheless follow a conserved sequence of mechanical and geometric transitions. This correlative approach mitigates morphology-only bias and makes otherwise hidden kinetic stages accessible. This strategy provides a general framework for tracking heterogeneous interfacial reactions, supporting nanoscale interpretation and control of reaction pathways.