Size-Dependent Electrochemical Oxidation of Silver Nanoparticles

Abstract

Here we quantify the electrochemical oxidation of Ag nanoparticles (NPs) as a function of size by electrostatically attaching Ag NPs synthesized by seed-mediated growth in the presence of citrate (diameter = 8 to 50 nm) to amine-functionalized indium-tin oxide coated glass electrodes (Glass/ITO), obtaining a linear sweep voltammogram from 0.1 V, where Ag(0) is stable, up to 1.0 V, and observing the peak potential (E(p)) for oxidation of Ag(0) to Ag(+). Electrostatic attachment to the organic linker presumably removes direct interactions between Ag and ITO and allows control over the total Ag coverage by altering the soaking time. This is important as both metal-electrode interactions and overall Ag coverage can affect E(p). E(p) shifts positive from an average of 275 to 382 mV as the Ag NP diameter increases for a constant Ag coverage and under conditions of planar diffusion, suggesting a shift in E(p) due to a thermodynamic shift in E(0) for the Ag/Ag(+) redox couple with size. The negative shift in E(p) with decreasing Ag NP radius follows the general trend predicted by theory and agrees with previous qualitative experimental observations. A better understanding of metal nanostructure oxidation is crucial considering their potential use in many different applications and the importance of metal corrosion processes at the nanoscale.

Displacement of voltammetric peaks with nanoparticles size: a nonextensive thermodynamic approach

“…Figure 1 : application of eq. 26 to the data of table 1 of ref [21]. The sizes correspond to the one measured by SEM (diameter D in nm).…”

“…Figure 2 : experimental variation of peak potentials for the system (points) described in ref. [21]. The solid curve is calculated from eq.…”

“…In particular, we will discuss two studies of Ivanova and Zamborini. The first considers silver particles [21]. These authors studied by voltammetry the oxidation of silver nanoparticles deposited on a glass electrode coated with indium-tin- Table 1 of their publication.…”

Detection, characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples

“…Typically, a few microliters of sample are deposited on the electrode and they are allowed to dry, preferably under an inert gas flow and by using slow evaporation rates to avoid agglomeration of the nanoparticles. Alternatively, the electrode surface can be modified to immobilize the nanoparticles by electrostatic interactions [193] or chemical reactions [194].…”

The unique electrochemical reactivity of small metal nanoparticles.

“…34,35 In our group we were studying the effect of size dependence on the change of the Ep value. [36][37][38] It is very well know that in many cases the reactivity of metal nanoparticles is directly correlated to the decrease in size. A decrease in size changes the coordination number of the atoms at the surface of the nanoparticle.…”