Time-resolved impact electrochemistry - A new method to determine diffusion coefficients of ions in solution

Saw, En Ning; Blanc, Niclas; Kanokkanchana, Kannasoot; Tschulik, Kristina

doi:10.1016/j.electacta.2018.06.013

Cited by 29 publications

(28 citation statements)

References 44 publications

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“…In this approach individual nanocatalysts are dispersed in an electrolyte solution and are electrically addressed during their Brownian motion-based impact at an inert microelectrode. [6][7][8][9][10][11][12][13][14] Applying a suitable potential, a steady-state catalytic current results at this nanocatalyst within microseconds 13,14 and a step-like increase in the current-time response is recorded (Figure 1). Figure 1.…”

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Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe₂O₄ Nanoparticles

et al. 2019

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Identifying the intrinsic electrocatalytic activity of nanomaterials is challenging, as their characterization usually requires additives and binders whose contributions are difficult to dissect. Herein, we use nano impact electrochemistry as an additive-free method to overcome this problem. Due to the efficient mass transport at individual catalyst nanoparticles, high current densities can be realized. High-resolution bright-field transmission electron microscopy and selected area diffraction studies of the catalyst particles before and after the experiments provide valuable insights in the transformation of the nanomaterials during harsh oxygen evolution reaction (OER) conditions. We demonstrate this for 4 nm sized CoFe 2 O 4 spinel nanoparticles. It is revealed that these particles retain their size and crystal structure even after OER at current densities as high as several kA•m −2 . The steady-state current scales with the particle size distribution and is limited by the diffusion of produced oxygen away from the particle. This versatilely applicable method provides new insights into intrinsic nanocatalyst activities, which is key to the efficient development of improved and precious metal-free catalysts for renewable energy technologies.

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confidence: 99%

Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe₂O₄ Nanoparticles

et al. 2019

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“…This makes necessary the study of the kinetics of the Zn deposition/dissolution reaction at the nanoscale as well, since the electrochemical behaviour of a material may differ at the nanoscale compared with the one at the macroscopic level [23]. In this respect, the electrode-particle collision method (often referred to as 'nanoimpacts method') has been shown to give important insights into the electrochemical behaviour in general, and the reaction kinetics in particular, of a variety of materials at the single particle level [24][25][26][27][28][29][30][31][32][33]. This method consists in dispersing a small amount of particles in solution, which, by virtue of their Brownian motion, may collide with the surface of a microelectrode.…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Fast electrodeposition of zinc onto single zinc nanoparticles

Zampardi

Compton

2020

J Solid State Electrochem

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The zinc deposition reaction onto metallic zinc has been investigated at the single particle level through the electrode-particle collision method in neutral solutions, and in respect of its dependence on the applied potential and the ionic strength of a sulphatecontaining solution. Depending on the concentration of sulphate ions in solution, different amounts of metallic zinc were deposited on the single Zn nanoparticles. Specifically, insights into the electron transfer kinetics at the single particles were obtained, indicating an electrically early reactant-like transition state, which is consistent with the rate-determining partial dehydration/de-complexation process. Such information on the reaction kinetics at the nanoscale is of vital importance for the development of more efficient and long-lasting nanostructured Zn-based negative electrodes for Zn-ion battery applications.

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“…Instead of this, electrochemical methods can be used to study even single particles quantitatively during an electrochemical reaction in situ in various aqueous electrolytes (nanoparticle impact) (Tschulik et al, 2014). If a NP is in contact with a polarized electrode, it can undergo several chemical reactions, like complete conversion of the particle itself (Batchelor-McAuley et al, 2015;Saw et al, 2018) or catalytically enhanced reactions at the particle surfaces (Cheng and Compton, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Although particles sizes (Batchelor-McAuley et al, 2015), compositions (Saw et al, 2016), reaction kinetics (Saw et al, 2017), reaction layer distances (Little et al, 2018), or diffusion coefficients (Saw et al, 2018) can be determined by NP impacts their reactions mechanism and additionally processes at the surfaces are today poorly understood and still under debate. Despite working with similar experimental conditions, different results were obtained.…”

Section: Introductionmentioning

confidence: 99%

“…From the dissolution rate, conclusions about the mechanism of the electrochemical oxidation can be drawn. In contrast, the formation of silver chloride (AgCl) is thermodynamically driven in the presence of chloride ions, which favors the oxidation of the silver nanoparticles and shifts it to lower potentials (Equation 2) (Toh et al, 2013;Saw et al, 2018). The reaction is supposed to proceed in a fast way, which can be observed by an instantaneous spectral change.…”

Section: Introductionmentioning

confidence: 99%

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Operando Studies of the Electrochemical Dissolution of Silver Nanoparticles in Nitrate Solutions Observed With Hyperspectral Dark-Field Microscopy

2020

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Since nanoparticles are frequently used in commercial applications, there is a huge demand to obtain deeper insights into processes at the nanoscale. Especially, catalysis, chemical and electrochemical reaction dynamics are still poorly understood. Thus, simultaneous and coupled opto-and spectro-electrochemical dark-field microscopy is used to study in situ and operando the electrochemically driven dissolution mechanism of single silver nanoparticles in the presence of nitrate ions as non-complexing counter-ions, herein. Hyperspectral imaging is used to probe the intrinsic localized surface plasmon resonance of individual silver nanospheres before, during and after their electrochemical oxidation on a transparent indium tin oxide (ITO) electrode. Furthermore, optical video imaging was performed for additional information. Based on the complete loss of spectral information and intensity, a dissolution of the particles during the reaction was concluded. This way it is revealed that the dissolution of individual particles proceeds over several seconds, indicating a hindrance by the nitrate ions. Only electrochemical analysis does not provide this insight as the measured current does not allow distinguishing between successive fast dissolution of one particle after another or slow dissolution of several particles in a concerted manner. For comparison, experiments were performed in the presence of chloride ions. It was observed that the silver chloride formation is an instantaneous process. Thus, it is possible to study and define the reaction dynamics on the single nanoparticle level in various electrochemical systems and electrolyte solutions. Accordingly, operando opto-and spectro-electrochemical studies allow us to conclude, that the oxidation of silver to solvated silver cations is a kinetically slow process, while the oxidation to silver chloride is fast. We propose this approach as a new method to study electrocatalyst materials, their transformation and degradation under operando conditions.

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Time-resolved impact electrochemistry - A new method to determine diffusion coefficients of ions in solution

Cited by 29 publications

References 44 publications

Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe₂O₄ Nanoparticles

Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe₂O₄ Nanoparticles

Fast electrodeposition of zinc onto single zinc nanoparticles

Operando Studies of the Electrochemical Dissolution of Silver Nanoparticles in Nitrate Solutions Observed With Hyperspectral Dark-Field Microscopy

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Time-resolved impact electrochemistry - A new method to determine diffusion coefficients of ions in solution

Cited by 29 publications

References 44 publications

Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe2O4 Nanoparticles

Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe2O4 Nanoparticles

Fast electrodeposition of zinc onto single zinc nanoparticles

Operando Studies of the Electrochemical Dissolution of Silver Nanoparticles in Nitrate Solutions Observed With Hyperspectral Dark-Field Microscopy

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Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe₂O₄ Nanoparticles

Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe₂O₄ Nanoparticles