Nanoparticle Impacts Show High‐Ionic‐Strength Citrate Avoids Aggregation of Silver Nanoparticles

Abstract

Quantitative analytical detection and sizing of silver nanoparticles is achieved by applying the new electrochemical method nanoparticle coulometry. For the first time, tri-sodium citrate is used as both an electrolyte and a nanoparticle stabilizing agent, allowing the individual particles to be addressed.

Impact and oxidation of single silver nanoparticles at electrode surfaces: one shot versus multiple events

“…We briefly examined the effect of the time constant on the current response for two reasons: (i) a number of studies in the literature, carried out with commercial potentiostats, appear to have employed a much longer time constant than considered for our studies; 17–19,24,53 and (ii) a long time constant will lead to a merging (summing) of discrete events, and it was worth testing if this allows the NP size to be recovered. Fig.…”

“…20) to 100 nm, 18 and it has consequently been argued that impact coulometry can be used as a method for in situ determination of the size, with nm resolution, of colloidal NPs of different materials such as Ag, 18–20 Cu, 22 Mo, 23 C-60, 24 Au 25 or to address colloidal stability and aggregation phenomena. 17,21 However, none of these studies provided a thorough analysis of the recorded I – t transients nor examined, with the same experimental setup, the landing of NPs with diameters spanning the range claimed. Moreover, recent work shows that the electrochemical dissolution of single NPs is a somewhat more complex process.…”

Electrochemical studies of silver nanoparticles: a guide for experimentalists and a perspective

“…6 Comparison of the size distributions of a sample of silver nanoparticles as determined by nanoparticle impact experiments (red columns, r = 9.2 AE 2.2 nm) in 0.1 M tri-sodium citrate solution and SEM analysis (black columns, r = 8.5 AE 3.5 nm); the inlay shows a SEM images of the analysed silver nanoparticles (adapted from ref. 36).…”

Femtomolar Detection of Silver Nanoparticles by Flow-Enhanced Direct-Impact Voltammetry at a Microelectrode Array

“…21,30,40 This is an improvement of more than 2 orders of magnitude in the detection limit, relative to that previously reported. 41 This extremely sensitive detection is a direct result of combining flow with a RAM electrode, increasing the signal-to-noise ratio. The presented method can be adjusted for sizing smaller NPs by choosing different array geometries in order to have suitable noise characteristics.…”