Single Ag Nanoparticle Spectroelectrochemistry via Dark-Field Scattering and Fluorescence Microscopies

Abstract

The spectroelectrochemical properties of individual luminescent, plasmonic silver nanoparticles (Ag NPs) are investigated using the combined methods of dark-field scattering (DFS) and photoluminescence (PL) spectroelectrochemistry. Individual NP light scattering and PL intensities are measured while the substrate’s electrochemical potential is controlled to produce and oxidize the NPs. The spectroelectrochemical responses of individual NPs are used to study heterogeneities in their redox properties not visible in bulk voltammetric measurements. Our studies show that the Ag NPs exhibit a range of redox potentials, and their statistical distribution is dependent on the electrolyte system used. No variations in the spectral profile of bulk NP samples are observed, implying no correlation between the redox potentials of individual NPs and the energy of emitted photons from fluorescent sites on Ag NPs. This is due to a negligible difference in the redox potentials for individual emissive sites on a given Ag NP and/or the shrinking of the polarizable bulk of the Ag NP.

Monitoring Simultaneous Electrochemical Reactions with Single Particle Imaging

“…[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. [14][15][16][17][18][19][20][21][22][23][24] Recently, Zhang et al [25] . [14][15][16][17][18][19][20][21][22][23][24] Recently, Zhang et al [25] .…”

“…[11][12][13] Several other groups have also studied the oxidation of single Ag NPs using electrochemical, optical, and correlated electrochemical-optical methods . [14][15][16][17][18][19][20][21][22][23][24] Recently, Zhang et al [25] . and Kwon et al [26] showed that oxidizing Ag NPs at highly positive potentials (> 1 V vs. Ag/AgCl) at a Au/Pt ultramicroelectrode (UME) produces Ag x O y on the surface of the Ag NPs, which then catalyzes water oxidation or hydrazine oxidation reactions.…”

Structural Change of a Single Ag Nanoparticle Observed by Dark‐field Microspectroscopy

“…Independent studies on optical and electrochemical properties of single AgNPs have been conducted . However, few studies have combined electrochemistry with the spectroscopic observation of a single metal nanoparticle …”

“…[8][9][10][11][12] However,f ew studies have combined electrochemistry with the spectroscopic observation of as ingle metal nanoparticle. [13][14][15] Dark-field microscopy (DFM), which provides the possibility of real-time opticals ensing with high sensitivity,h as been used to track andd irectly observe chemical reactions on single plasmonic nanoparticles. [17][18][19][20][21][22][23] Mulvaney and co-workersh ave demonstrated that it is feasible to modulate the optical properties of single gold nanorods by using electrochemical charge injectiont od irectly observe ar edox reactiono ns ingle gold nanorod in real time using DFM.…”

Electrochemical synthesis of Au@semiconductor core–shell nanocrystals guided by single particle plasmonic imaging

“…On the other hand, it provides an opportunity to monitor the changes occurring on the NPs, for example, the in situ growth, etching, and chemical reactions. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Therefore, from the perspective of photocatalysts' synthesis, the growth of the semiconductor or metal could be monitored in real-time via dark-eld microscopy (DFM) by tracking the LSPR scattering variation. It will provide comprehensive understanding of the growth mechanism, as well as tailor the properties of photocatalysts precisely.…”