Single Particle Electrochemical Oxidation of Polyvinylpyrrolidone-Capped Silver Nanospheres, Nanocubes, and Nanoplates in Potassium Nitrate and Potassium Hydroxide Solutions

Abstract

Single particle electrochemical oxidation of poly(vinylpyrrolidone)-capped silver nanoparticles at a microdisk electrode was investigated as a function of particle shape (spheres, cubes, and plates) in potassium nitrate and potassium hydroxide solutions. In potassium nitrate, extreme anodic potentials (≥1500 mV vs. Ag/AgCl (3 M KCl)) were necessary to achieve oxidation, while lower anodic potentials were required in potassium hydroxide (≥900 mV vs. Ag/AgCl (saturated KCl)). Upon oxidation, silver oxide is formed, readily catalyzing water oxidation, producing a spike-step current response. The spike duration for each particle was used to probe effects of particle shape on the oxidation mechanism, and is substantially shorter in nitrate at the large overpotentials than in hydroxide solution. The integration of current spikes indicate initial oxidation to Ag(I) in a mixed-valance complex. In both electrolytes, the rate of silver oxidation strongly depends on silver content of the nanoparticles, rather than the shape-dependent variable–surface area. The step height, which reflects rate of water oxidation, also tracks the silver content more so than shape. Results were compared to those from less-protected citrate-capped particles and suggest that contributions of the polymer capping ligand to kinetic barriers to oxidation are negligible under these conditions.

Size-Optimized Silver Nanowires with Graphene Oxide for High-Performance Transparent Electrodes

“…For the UV-vis curves of Ag-based NWs, the peaks at 352 nm and 390 nm are attributed to the characteristics of one-dimensional nanowires while the tailing phenomena during 600 ∼ 800 nm is caused by Ag nanoparticles. 32 As shown in Fig. 2a, except for the sample with 83 nm, the other two both show classic characteristic peaks at 352 nm and 390 nm for nanowires, without tailing phenomena, meaning well-defined nanowire morphology.…”

Electrochemical Detection and Analysis of Various Current Responses of a Single Ag Nanoparticle Collision in an Alkaline Electrolyte Solution

“…This is because the detection of Ag NPs based on self-oxidation or the blocking strategy requires a significantly large NP size of at least sub-micrometers. Therefore, the observation of single Ag NP collision using the EA method is advantageous in sensitivity compared to recent studies on single Ag NP collision using a blocking strategy or self-oxidation [32,34,35]. This has helped to avoid the problem in which a signal could not be observed when the NPs were small [12,20].…”

Electronic Circuit Simulations as a Tool to Understand Distorted Signals in Single-Entity Electrochemistry

“…The emerging field of “single-entity electrochemistry” (SEE) refers to measurement and interpretation of the electrical transient signals generated when a single entity, e.g., a nanoparticle, a single molecule, a droplet, a micelle, or a living cell, undergoes electrochemical processes at suitable interfaces, including micro- and nano-electrodes or -pipets, nanopores, etc. − The technique’s capability to probe a signal from single entities makes it powerful for delivering both individual and statistical information on these entities. This makes it beneficial for a broad range of investigations, including nanoparticle characterizations and dynamic transformations, − agglomeration study, ion diffusion and solvation studies, , detection and identification of single bacteria or viruses, − catalytic activity investigation of single enzymes, detection of conformation changes of a single DNA, single-molecule detection, battery material characterization, and investigation of the catalytic activity of individual nanoparticles. − …”