Nanoimpacts at Active and Partially Active Electrodes: Insights and Limitations

Abstract

While the electrochemical nanoimpact technique has recently emerged as am ethod of studying single entities,i ti s limited by requirement of ac atalytically active particle impacting an inert electrode.W es how that an active particleactive electrode can provide mechanistic insight into electrochemical reactions.W hen an individual Pt electrocatalyst adsorbs to the surface of ap artially active electrode,f urther reduction of electrode-produced species can proceed on the nanocatalyst. Current transients obtained during hydrogen evolution allow simultaneous measurement of the Pt catalyst over different length scales,s ize dependency suggests Ha tom intercalation as ac atalytic deactivation mechanism. Although results showt hat outer-sphere redoxp robes are unproductive for particle characterization, the breadth of inner-sphere electrochemical reactions makes this ap romising method for understanding the properties of catalytic nanomaterials,one at atime.

Tuning the Electrode Activity to Expose Transformational and Electrocatalytic Characteristics of Individual Nanoparticles by Nanoimpact Electrochemistry

“…[18,19,24] On the other hand, NIE was employed to determine the electrocatalytic activity of individual NPs. Many electrocatalytic reactions have been inspected including the oxygen evolution, [25,26] or reduction, [27,28] hydrogen evolution, [29][30][31][32][33] or oxidation, [34] hydrogen peroxide oxidation [35] and reduction, [36] and hydrazine oxidation reactions. [37][38][39] Besides, these reactions were inspected at a variety of NPs such as metals (Pd, [29] Pt, [27,30,34,36,37,39] Au, [30,31] ), metal oxides (CoFe 2 O 4 , [25] IrO x, [35] Pt@TiO 2, [28] Ni(OH) 2 [40] ) or carbon materials.…”

“…By varying the activity of the electrode, deeper mechanistic insights were reached regarding the electrocatalysis at the NP. [32] Herein, we will use a catalytically active electrode (Au UME) to suppress the catalytic response of the NPs and therefore to study their redox transformation (Scheme 1a). Alternatively, a catalytically inactive electrode (C UME) will allow probing both the transformation and the electrocatalytic activity of the NPs (Scheme 1b).…”

Adiabatic versus Non-Adiabatic Electron Transfer at 2D Electrode Materials

“…Co-located Raman microscopy and field emission-scanning electron microscopy allow unambiguous characterization of the sites of the electrochemical measurements in a correlative multi-microscopy approach, 49,57 while the copper substrate surface crystallography upon which the graphene sits, can also be mapped with electron backscatter diffraction (EBSD) to determine any influence on the electrochemical response. [58][59][60][61][62][63] We focus on the ET kinetics of [Ru(NH3)6] 3+/2+ , a classic example of OS-ET, [64][65][66][67][68] which has been used for studies of outer sphere electrochemistry at graphene, 40,69 and does not adsorb on graphene at a detectable level. 70 We establish that the ET rate is in the order monolayer > bilayer > multilayer graphene on copper.…”

Detection and Characterization of Single Particles by Electrochemical Impedance Spectroscopy

“…Single-entity electrochemistry has recently emerged as a way to study the properties of single nano- and microparticles. − Individual particles are interrogated, one by one, to build a bottom-up understanding that captures the heterogeneity among particles in an ensemble. , A common scheme is the “nano-impact” technique, in which microelectrodes and low-noise equipment are used to detect single particles when they stochastically collide with an electrode. , The current response associated with the impact event can be used, for example, to determine the size of an insulating particle − or to monitor the activity of an electrocatalyst. ,− …”