Surface-State-Dependent Electrochemical Behavior in Single-Particle Collision Oxidation of Silver Nanoparticles

Single-particle collision electrochemistry probes nanoparticle behavior at electrode interfaces through transient current signals generated during particle impact. Because these signals arise from localized nanoparticle-electrode interactions, surface states can strongly influence contact behavior and transient current features. Here, Au ultramicroelectrode (UME) surface states were varied by sequential polishing to examine the collision oxidation of 30 nm Ag nanoparticles (Ag NPs). Rougher UME surface states produced more diverse transient peak shapes, including shoulder-containing, undulating, and multipeak events, indicating more complex particle-electrode contact pathways during collision oxidation. Surface smoothing shifted the responses toward simple asymmetric parabolic peaks, shortened the event duration, and favored more direct oxidation behavior approaching two-electron oxidation. These findings reveal that the electrode surface state modulates the collision oxidation behavior of individual Ag NPs and should be considered during signal analysis to reduce surface-state-induced bias in signal assignment and mechanistic interpretation.