Nanoimpacts Reveal the Electron‐Transfer Kinetics of the Ferrocene/Ferrocenium Couple Immobilised on Graphene Nanoplatelets

Abstract

The kinetics of the ferrocene/ferrocenium (Cp2Fe/Cp2Fe+) redox couple immobilised on graphene nanoplatelets (GNPs) in aqueous solution are evaluated by using the nanoimpacts method. Single GNPs modified with poly(vinylferrocene) are allowed to impact a microelectrode. For the duration (ca. 10–100 ms) of the impacts, the GNP adopts the potential of the electrode and acts as a “chemically modified nanoelectrode”. The study of individual impacts facilitates the resolution of fast electron‐transfer kinetics that, for the Cp2Fe/Cp2Fe+ couple, is shown to be at least 3±1 s−1.

Impacts reveal and quantify monolayer adsorption on single alumina particles

“…[26] Therefore, in order to genuinely quantify adsorption of the molecules on the particles, the study of impacts of individual particles is essential. [13,27] Particle Impact Chronoamperometry With the aim of quantifying the adsorption of different molecules on single alumina particles, impact chronoamperometry was conducted. The cyclic voltammetry in the preceding section allows estimations of the minimum potentials required for impacts of individual modified alumina particle at a µ-CE to be seen although a large overpotential was typically applied to fully drive the exhaustive redox of the surface bound molecules.…”

“…The cyclic voltammetry in the preceding section allows estimations of the minimum potentials required for impacts of individual modified alumina particle at a µ-CE to be seen although a large overpotential was typically applied to fully drive the exhaustive redox of the surface bound molecules. [15,27,28] The oxidation of H2C-Al2O3 and PVFc-Al2O3 should take place when the applied potential is more positive than +0.42 and +0.45 V, and the reduction of AQ-Al2O3 and TCBQ-Al2O3 should occur when the applied potential is more negative than -0.34 and +0.28 V, respectively. Table 2a.…”

Electrocatalytic Reduction of Hydrogen Peroxide by Pd−Ag Nanoparticles Based on the Collisional Approach

“…From molecular level to cell level, this technique can provide abundant information about the dynamic processes at single event level, including frequency detection, charge transfer and catalytic mechanisms. The particles can be classified into hard particles like metal particles (Pt, [6] Ag, [7] Au, [8] Ni, [9] AgÀ Hg alloy [10] ), oxides (IrO 2, [11] TiO 2, [12] CeO 2 [13] ), organic nanoparticles [14] or polymer, [15][16][17] and soft particles such as droplets, [18][19][20][21][22][23][24][25][26] liposomes, viruses, [29][30] vesicles, [31][32] macromolecules [33][34][35] and cells. The particles can be classified into hard particles like metal particles (Pt, [6] Ag, [7] Au, [8] Ni, [9] AgÀ Hg alloy [10] ), oxides (IrO 2, [11] TiO 2, [12] CeO 2 [13] ), organic nanoparticles [14] or polymer, [15][16][17] and soft particles such as droplets, [18][19][20][21][22]…”

Catalytic Single-Particle Nano-Impacts: Theory and Experiment. Poly(vinylferrocene)-Modified Graphene Nanoplatelet Mediated l-Cysteine Oxidation

“…Note that the use of individual GNPs circumvents the non-ideal voltammetry 6,[21][22][23][24] of large ensembles of particles measured at macro-and microelectrodes, and so provides a more reliable route to measure electron transfer kinetics and mechanisms. 20 In this work L-cysteine, an amino acid with a thiol group (Scheme 1), 18 is employed as the electroactive species under observation. We demonstrate the use of poly(vinylferrocene) modified graphene nanoplatelets (PVFc-GNP) as a mediator for the oxidation of L-cysteine in aqueous solutions and develop the theory of catalytic single particle nano-impacts.…”