Insights into electrochemical reactions by differential electrochemical mass spectrometry

One of the main challenges in metal-air batteries is the selection of a suitable electrolyte that is characterized by high oxygen solubility, low viscosity, a liquid state and low vapor pressure across a wide temperature range, and stability across a wide potential window. Herein, a new method based on a thin layer flow through cell coupled to a mass spectrometer through a porous Teflon membrane is described that allows the determination of the solubility of volatile species and their diffusion coefficients in aqueous and nonaqueous solutions. The method makes use of the fact that at low flow rates the rate of species entering the vacuum system, and thus the ion current, is proportional to the concentration times the flow rate (c⋅u) and independent of the diffusion coefficient. The limit at high flow rates is proportional to D2/3·c·u1/3 . Oxygen concentrations and diffusion coefficients in aqueous electrolytes that contain Li(+) and K(+) and organic solvents that contain Li(+) , K(+) , and Mg(2+) , such as propylene carbonate, dimethyl sulfoxide tetraglyme, and N-methyl-2-pyrrolidone, have been determined by using different flow rates in the range of 0.1 to 80 μL s(-1) . This method appears to be quite reliable, as can be seen by a comparison of the results obtained herein with available literature data. The solubility and diffusion coefficient values of O2 decrease as the concentration of salt in the electrolyte was increased due to a "salting out" effect.

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“…Onlined ifferential electrochemical mass spectrometry (DEMS) [9][10][11] in combination with ad ual thin layer flow through…”

Section: Introductionmentioning

confidence: 99%

Determining Solubility and Diffusivity by Using a Flow Cell Coupled to a Mass Spectrometer

et al. 2016

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“…Instead, pH buffering supporting electrolytes up to a concentration of 0.5 mol L À1 can be applied to increase spacetime yields of electrolysis with poorly water soluble n-carboxylic acids and their derived n-carboxylates. [49,46] Furthermore spectroelectrochemical studies [50][51][52] or differential electrochemical mass spectrometry [53][54][55] can reveal reaction mechanisms and suggest solutions for future reaction engineering. Therefore, in addition to alternative buffer systems, also rotating disk electrode studies with a well-defined diffusion layer thickness [29]- [31] or exploiting electrochemical flow-cells with defined fluid dynamics [47,48] are recommended to shed more light on the mechanistic correla-tion between reaction rate and local pH shift during C 8 oxidation under varying environmental conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Simultaneously, fluorescent probes might be applied to facilitate visualization of the vesicle-and bilayer-like structures. [49,46] Furthermore spectroelectrochemical studies [50][51][52] or differential electrochemical mass spectrometry [53][54][55] can reveal reaction mechanisms and suggest solutions for future reaction engineering . 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57…”

Section: Discussionmentioning

confidence: 99%

Deterioration of Aqueous n‐Octanoate Electrolysis with Electrolytic Conductivity Collapse Caused by the Formation of n‐Octanoic Acid/n‐Octanoate Agglomerates

Urban

2017

ChemElectroChem

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Electroorganic synthesis performed in water (as a green solvent) bears potential for the selective production of chemicals from renewable power. Yet, the limited solubility of organic molecules hampers their aqueous electrolysis. For the proposed platform chemical n-octanoic acid/n-octanoate, both summarized as C 8 , it is shown that the aqueous electrolysis of C 8 can be performed successfully, provided that certain requirements are fulfilled. It is evidenced that the often-overlooked local pH shift in the proximity of the electrode can lead to the formation of large C 8 agglomerates (e. g. vesicles, bilayers), which deteriorate the electrolysis by minimizing the electrolytic conductivity. It is stressed that pH-buffering electrolytes have to be preferred to pH-neutral supporting electrolytes for C 8 electrolysis to achieve improved spaceÀtime yields. Cyclic voltammetry, particle-size analysis through dynamic light scattering, and light microscopy characterize the nature of these agglomerates.

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“…298,299 The main component of DEMS is a non-wetting porous membrane that allows volatile compounds to evaporate into a two-step vacuum as a function of their formation rate, hence the name "differential". 300 5.2.2.1 Thin-layer DEMS cells. Modern DEMS systems, as described by Abd-El-Latif et al, 300 are generally built in a thinlayer configuration, where an electrode is placed on one side and a porous membrane on the other side.…”

Section: Differential Electrochemical Mass Spectrometry (Dems)mentioning

confidence: 99%

“…300 5.2.2.1 Thin-layer DEMS cells. Modern DEMS systems, as described by Abd-El-Latif et al, 300 are generally built in a thinlayer configuration, where an electrode is placed on one side and a porous membrane on the other side. The electrochemical reaction products have to cross from the electrode to the other side of the cell to pass the membrane, causing response times of up to 2 s.…”

Section: Differential Electrochemical Mass Spectrometry (Dems)mentioning

confidence: 99%

Spectroelectrochemistry, the future of visualizing electrode processes by hyphenating electrochemistry with spectroscopic techniques

Lozeman

Führer

Olthuis

et al. 2020

Analyst

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The combination of electrochemistry and spectroscopy, known as spectroelectrochemistry (SEC), is an already established approach. By combining these two techniques, the relevance of the data obtained is greater than what it would be when using them independently. A number of review papers have been published on this subject, mostly written for experts in the field and focused on recent advances. In this review, written for both the novice in the field and the more experienced reader, the focus is not on the past but on the future. The scope is narrowed down to four techniques the authors claim to have the most potential for the future, namely: infrared spectroelectrochemistry (IR-SEC), Raman spectroelectrochemistry (Raman-SEC), nuclear magnetic resonance spectroelectrochemistry (NMR-SEC) and, perhaps slightly more controversial but certainly promising, electrochemistry mass-spectrometry (EC-MS).

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Insights into electrochemical reactions by differential electrochemical mass spectrometry

Cited by 59 publications

References 61 publications

Determining Solubility and Diffusivity by Using a Flow Cell Coupled to a Mass Spectrometer

Determining Solubility and Diffusivity by Using a Flow Cell Coupled to a Mass Spectrometer

Deterioration of Aqueous n‐Octanoate Electrolysis with Electrolytic Conductivity Collapse Caused by the Formation of n‐Octanoic Acid/n‐Octanoate Agglomerates

Spectroelectrochemistry, the future of visualizing electrode processes by hyphenating electrochemistry with spectroscopic techniques

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