Visualizing the Effect of Partial Oxide Formation on Single Silver Nanoparticle Electrodissolution

Abstract

The impact of heterogeneous surface oxide formation on the electrochemical performance of single silver nanoparticles is explored using in situ superlocalization optical microscopy. Silver nanoparticles are well-known to form a natural oxide layer on their surface, but the effect of this oxide layer on electrochemical reactions is not well understood. Here we track the temporal and spatial dependence of electrodissolution of single silver nanoparticles in order to study the role of surface oxide layers on electrochemical reactions. Heterogeneity in electrodissolution kinetics is observed by following the time-dependent loss in scattering intensity from individual silver nanoparticles using dark-field scattering. Both fast and slow dissolution kinetics are observed, with the dominant pathway changing as a function of applied potential. To understand this, superlocalization imaging is employed to follow the spatial variance of the electrodissolution process and reveals that the silver nanoparticles undergo electrodissolution in either a spatially symmetric or asymmetric manner. We hypothesize that asymmetric dissolution events are due to heterogeneity in the exposed silver sites on the nanoparticle surface because of incomplete surface oxide formation. Polarization-resolved measurements support this hypothesis by revealing anisotropic dissolution of the nanoparticles over time. By tracking the electrodissolution behavior of silver nanoparticles in both the temporal and spatial domains, we provide an improved understanding of how heterogeneity in electrochemical reactions is impacted by nanoparticle surface properties.

Monitoring Simultaneous Electrochemical Reactions with Single Particle Imaging

“…[10] We also tracked the spatial origin of the scattering as a function of time and potential and found that NPs undergo either isotropic or anisotropic dissolution, due to the heterogeneous formation of Ag x O y layers on the particle surfaces. [10] We also tracked the spatial origin of the scattering as a function of time and potential and found that NPs undergo either isotropic or anisotropic dissolution, due to the heterogeneous formation of Ag x O y layers on the particle surfaces.…”

“…For example, surface oxides on Ag NPs can reduce SERS signals by damping the plasmondriven electromagnetic field enhancements near the particle surface. [10] Recently, we showed how nanoscale heterogeneity of surface oxide layers impacts the kinetics and morphology of single Ag NPs during electrodissolution using dark-field microscopy. [10] Recently, we showed how nanoscale heterogeneity of surface oxide layers impacts the kinetics and morphology of single Ag NPs during electrodissolution using dark-field microscopy.…”

“…[8,9] Surface oxide layers also impact the electrochemical behavior of Ag NPs, affecting both their performance as electrodes as well as their electrodissolution kinetics during silver oxidation. [10] Electrochemical studies at the single particle level are of great interest because they reveal particle-to-particle heterogeneity and provide an understanding of the underlying mechanisms that may be hidden in ensemble electrochemical measurements. [10] Electrochemical studies at the single particle level are of great interest because they reveal particle-to-particle heterogeneity and provide an understanding of the underlying mechanisms that may be hidden in ensemble electrochemical measurements.…”

“…[10] Recently, we showed how nanoscale heterogeneity of surface oxide layers impacts the kinetics and morphology of single Ag NPs during electrodissolution using dark-field microscopy. [10] Electrochemical studies at the single particle level are of great interest because they reveal particle-to-particle heterogeneity and provide an understanding of the underlying mechanisms that may be hidden in ensemble electrochemical measurements. [11][12][13] Several other groups have also studied the oxidation of single Ag NPs using electrochemical, optical, and correlated electrochemical-optical methods .…”

Coupled Optical and Electrochemical Probing of Silver Nanoparticle Destruction in a Reaction Layer

“…[14] Although spectroscopic information is attainable,m uch of the work in the literature has focusedo nt he intensity of the scattered light from individual particles and its alteration during the course of their oxidation.T his allows the processes to be dynamically monitored and yields potentiali nsighti nto the reaction kinetics at the nanoscale. [15][16][17] Further development of holographict echniquest oe nable NP tracking in three dimensions has enabled the simultaneous in situ tracking of particlesadjacentt oa nd at an electrochemical interface. [18][19][20] Elsewhere, the trackingo fN P trajectories is aw ell-established techniquef or studies into areas including single NP growth or single NP reactions using as ingle NP spectrometer.…”