Landing and Catalytic Characterization of Individual Nanoparticles on Electrode Surfaces

Abstract

We demonstrate a novel and versatile pipetbased approach to study the landing of individual nanoparticles (NPs) on various electrode materials without any need for encapsulation or fabrication of complex substrate electrode structures, providing great flexibility with respect to electrode materials. Because of the small electrode area defined by the pipet dimensions, the background current is low, allowing for the detection of minute current signals with good time resolution. This approach was used to characterize the potential-dependent activity of Au NPs and to measure the catalytic activity of a single NP on a TEM grid, combining electrochemical and physical characterization at the single NP level for the first time. Such measurements open up the possibility of studying the relation between the size, structure and activity of catalyst particles unambiguously.

Scanning Electrochemical Cell Microscopy: A Versatile Technique for Nanoscale Electrochemistry and Functional Imaging

“…Finally, we have also exploited the ability of SECCM to form a nanoscopic electrochemical cell to perform nanoparticle landing experiments (92). The probe was filled with a colloidal solution of gold nanoparticles (AuNPs) in an electrolyte solution, and the meniscus was brought into contact with a 'collector' electrode.…”

Time-Resolved Detection and Analysis of Single Nanoparticle Electrocatalytic Impacts

“…This is because the electrochemical cell is formed by meniscus confinement, rather than electrode encapsulation ( Figure 1). 13 Despite these innovations, detailed analysis of the form of the current-time profile which is the primary signal for the landing (and detachment) of a single NP on an electrode has not yet been forthcoming, but would represent a huge advance towards understanding the impact process. Herein, we are able to analyze this process as never before and deduce key information on the NP arrival and release process from individual impact transients.…”

“…In this paper we use SECCM 13 to investigate H2O2 oxidation at ruthenium oxide (RuOx) NPs, determining the NP landing characteristics and the distribution of kinetics currents for individual impacts within an ensemble of colliding NPs, with unprecedented time resolution. The heterogeneous kinetics of H2O2 electro-oxidation has been studied extensively at a variety of nanomaterials, 13 among which several metal oxides appear to be promising, particularly for bioanalytical applications, due to the biocompatibility and robust electrocatalytic performance.…”

“…The heterogeneous kinetics of H2O2 electro-oxidation has been studied extensively at a variety of nanomaterials, 13 among which several metal oxides appear to be promising, particularly for bioanalytical applications, due to the biocompatibility and robust electrocatalytic performance. [14][15][16][17] RuOx is especially interesting as it catalyzes H2O2 electro-oxidation at relatively low overpotentials in physiological environments.…”

High-Speed Electrochemical Imaging

“…46,47 As highlighted above, the high-speed scanning method becomes even more powerful when an additional parameter, such as time or the reaction driving potential are brought to bear on a series of images, and this is particularly the case for complex electrocatalytic surfaces. The set of frames in Figure 4b depicts the reactivity of NPs at a variety of substrate potentials.…”