Electrochemistry of Single Nanoparticles via Electrocatalytic Amplification

Abstract

Recent experiments on the observation of collisions of single nanoparticles (NPs) with an electrode through amplification of the current by electrocatalysis are described. Systems in which the particles adhere to the electrode upon collision produce a step and staircase response, while those in which particles only interact for a short time with the electrode produce a spike or blip, with little change in the steady state current. Examples of both behaviors, e. g., Pt NPs on a Au electrode for hydrazine oxidation (staircase response) and IrOx NPs on a Pt electrode for water oxidation (blip response) are shown. Controlling the nature of the electrode surface is important in generating useful responses, for example, in the case of gold NPs on an oxidized Pt electrode for borohydride oxidation.

Transient Interactions of Agglomerates of Sensitized TiO2Nanoparticles in Colloidal Suspensions

“…After the initial transient that result from turning the illumination on, the oscillations due to DSNPs interacting with FTO ultra-microelectrode can be seen (e.g., Figure 6a and the inset). The observation of current oscillations instead of step wise behavior 2,8 is indicative of short term interaction between particles and the electrode. The DSNPs clearly show higher magnitude for the PEC current oscillations compared to bare TiO 2 NPs.…”

“…The field of stochastic electrochemistry for the detection of nanoparticles (NPs) has rapidly gained attention since the initial experiments proposed for the amperometric detection of electrocatalytic NPs by the Bard group 1-3 and others. [4][5][6][7] The stochastic studies have rapidly expanded to include contact, 2,3,8 i.e., irreversible interactions between NPs and the non-contact (reversible) 9,10 interactions between electrodes and NPs of metals. Electrochemical studies of discrete interactions in the "nano-impact" method by Compton 11-16 and co-workers include the complete electrolysis of NPs.…”

Observation of Electrocatalytic Amplification of Iridium Oxide (IrOx) Single Nanoparticle Collision on Copper Ultramicroelectrodes

“…On the Au UME, the current transient signal could be observed, but is also not very reproducible and it was not observed on the C fiber UME. [3][4][5] As like this, the observation of NP collision is very sensitive to the UME material and treatment.…”

“…[1][2][3][4] A system consists of a nanoparticle (NP) and UME, and an electrocatalytic reaction is required for the observation of single nanoparticle collisions on the UME by electrochemical amplification method. The materials for the NP and UME should have different electrocatalytic activities for the reaction.…”

“…Interestingly, the two cases show different current responses: a staircase response and a blip response, respectively. 4,5 In the case of staircase response, the NPs adhere to the electrode surface and continues to catalyze the electrocatalytic reaction. The Pt NP collision on the Au UME shows the staircase current increase.…”