Observation of Multipeak Collision Behavior During the Electro‐Oxidation of Single Ag Nanoparticles Based on Au Nanopore Electrode

ABSTRACT

Stochastic single‐nanoparticle collision amperometry was employed to investigate the dynamic electro‐oxidation behavior of individual Ag nanoparticles (NPs) at Au nanoelectrodes. Our results reveal that Ag NPs undergo partial oxidation during a single collision event, which manifests as a series of discrete “sub‐events” (ranging from 1 to ∼10 per collision) within a ∼20 ms interval. Notably, Au nanopore electrodes (NPEs) exhibit a significantly higher average number of sub‐events (4.2) and longer interpeak durations (∼5 ms) compared to planar nanodisk electrodes (NDEs, average 1.9 sub‐events, ∼3 ms duration). Correspondingly, the oxidation fraction of 60 nm Ag NPs increases from 16% (NDE) to 32% (NPE). This distinct multipeak behavior is attributed to the nanoconfinement effect of the porous structure, which sterically hinders the escape of NPs and alters the electrical double‐layer (EDL) interactions, effectively acting as an electrochemical trap. Furthermore, specific anions such as chloride were found to induce rapid surface passivation, severely limiting the number of sub‐events. These findings provide deep insights into the intrinsic mass transport and interfacial electron transfer dynamics of single nanoparticles in confined spaces.