Chemically Resolved Transient Collision Events of Single Electrocatalytic Nanoparticles

Abstract

Here we report the use of fast-scan cyclic voltammetry (FSCV) to study transient collision and immobilization events of single electrocatalytic metal nanoparticles (NPs) on an inert electrode. In this study, a fast, repetitive voltage signal is continuously scanned on an ultramicroelectrode and its faradaic signal is recorded. Electrocatalytically active metal NPs are allowed to collide and immobilize on the electrode resulting in the direct recording of the transient voltammetric response of single NPs. This approach enables one to obtain the transient voltammetric response and electrocatalytic effects of single catalytic NPs as they interact with an inert electrode. The use of FSCV has enabled us to obtain chemical information, which is otherwise difficult to study with previous amperometric methods.

Earth‐Abundant Nanomaterials for Oxygen Reduction

“…[231,232] Tr ansient particle-electrode collision has been reported as au seful methodology in studying the electrocatalysis at the single NP level. [233][234][235] It is based on al arge current amplification that happens when ac atalytic NP collides with the inert microelectrode surface during the reaction. By modifying the NPs,t he applied potential, and the indicator concentration, as eries of time-dependent Faradaic-response profiles can be obtained, allowing the study of electrontransfer kinetics at the microscale.S canning electrochemical microscopy (SECM) is another efficient tool for electrocatalytic activity investigation on the microscale.C atalytic NPs attached on the inert electrode are scanned by the nanosized tips in the SECM during an electrochemical reaction process.T he tip current is recorded as af unction of x-y position or distance,offering electrochemical mapping of the target position with spatial resolution.…”

Time-Resolved Detection and Analysis of Single Nanoparticle Electrocatalytic Impacts

“…[1][2][3] An interesting approach for observing the electrochemical properties of catalytic NPs is to monitor their impact (or landing) from solution onto a collector electrode, as introduced by Bard et al, 4,5 and developed by several groups. [6][7][8][9][10][11][12] In order to resolve such impacts, the use of a small-sized ultramicroelectrode (UME) is mandatory to reduce both background currents and the impact frequency. To enhance the impact signal to background current, electrode surfaces have been modified with Hg or Bi 7 and borondoped diamond 12 has also been used as an UME material.…”

Addressing Colloidal Stability for Unambiguous Electroanalysis of Single Nanoparticle Impacts

“…We broadly define NIE as any method based on the electrochemical detection of discrete NPs in solution as they collide with the surface of an electrode. [1][2][3][4][5][6][7] The ability to probe individual microscopic particles in solution with UMEs has inspired fundamental studies of single NP electrochemistry and NP/electrode interactions, [8][9][10][11][12][13][14][15][16][17] diffusive and electro/magnetophoretic particle transport, [18][19][20][21][22] and the development of electrochemical bioassays with single-molecule sensitivity. [23][24] Colloidal stability [25][26] is of critical importance for the accurate interpretation of NP/electrode impacts.…”

“…The establishment of quantitative correlations between NIE and NTA is currently underway to develop cross-correlative analytical standards, which will significantly aid in ongoing pursuits to develop NIE for applications such as colloidal NP size characterizations, 43 evaluations of catalytic activities at the single NP level, 11,13 and strategies for ultrasensitive bioanalysis. 23 ASSOCIATED CONTENT Supporting Information.…”