Electrochemical Real‐Time Mass Spectrometry (EC‐RTMS): Monitoring Electrochemical Reaction Products in Real Time

Khanipour, Peyman; Löffler, Mario; Reichert, Andreas M.; Haase, Felix T.; Mayrhofer, Karl Johann Jakob; Katsounaros, Ioannis

doi:10.1002/anie.201901923

Cited by 66 publications

(52 citation statements)

References 46 publications

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“…Combined with an electrochemical cell, mass spectrometry (MS) is ap romising technique to probe reactive species at the electrode-electrolyte interface.T od ate,s everal operando/in situ electrochemical MS techniques,s uch as differential electrochemical mass spectrometry (DEMS), [9] on-line electrochemical mass spectrometry (OLEMS), [16] electrochemical real-time mass spectrometry (EC-RTMS), [17] and selected-ion flow tube mass spectrometry (SIFT-MS), [18] have been developed to elucidate mechanistic pathways for eCO 2 RR. Regardless of the detailed design of each technique, CO 2 is invariably introduced to the electrochemical cell using aC O 2 -saturated liquid electrolyte,w hich greatly limits the capability of the techniques.F or example,d ue to the low solubility of CO 2 in aqueous electrolytes (approximately 30 mM), the highest eCO 2 RR current density that can be achieved using aC O 2 -saturated aqueous electrolyte is approximately 40 mA cm À2 ,w hich is far below industrially relevant current densities (> 100 mA cm À2 ).…”

Section: Introductionmentioning

confidence: 99%

Flow Electrolyzer Mass Spectrometry with a Gas‐Diffusion Electrode Design

Hasa

Jouny

et al. 2020

Angew Chem Int Ed

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Operando mass spectrometry is a powerful technique to probe reaction intermediates near the surface of catalyst in electrochemical systems. For electrochemical reactions involving gas reactants, conventional operando mass spectrometry struggles in detecting reaction intermediates because the batch‐type electrochemical reactor can only handle a very limited current density due to the low solubility of gas reactant(s). Herein, we developed a new technique, namely flow electrolyzer mass spectrometry (FEMS), by incorporating a gas‐diffusion electrode design, which enables the detection of reactive volatile or gaseous species at high operating current densities (>100 mA cm−2). We investigated the electrochemical carbon monoxide reduction reaction (eCORR) on polycrystalline copper and elucidated the oxygen incorporation mechanism in the acetaldehyde formation. Combining FEMS and isotopic labelling, we showed that the oxygen in the as‐formed acetaldehyde intermediate originates from the reactant CO, while ethanol and n‐propanol contained mainly solvent oxygen. The observation provides direct experimental evidence of an isotopic scrambling mechanism.

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Section: Introductionmentioning

confidence: 99%

Flow Electrolyzer Mass Spectrometry with a Gas‐Diffusion Electrode Design

Hasa

Jouny

et al. 2020

Angew Chem Int Ed

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“…ESI can be coupled with a separate electrochemical (EC) flow reactor [14] or directly used as an electrochemical cell [3c, 15] for various studies such as identification of reaction intermediates, [14d–f] examination of electrochemical reactions, [14a, 15b] and to mimic biologically relevant electrochemical reactions [16] . However, the electrochemical reactions occurring in such electrochemical cells or ESI emitters reflect the reaction behavior in the bulk phase and do not possess the acceleration phenomenon.…”

Section: Figurementioning

confidence: 99%

Accelerating Electrochemical Reactions in a Voltage‐Controlled Interfacial Microreactor

et al. 2020

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Microdroplet chemistry is attracting increasing attention for accelerated reactions at the solution-air interface. We report herein a voltage-controlled interfacial microreactor that enables acceleration of electrochemical reactions which are not observed in bulk or conventional electrochemical cells. The microreactor is formed at the interface of the Taylor cone in an electrospray emitter with a large orifice, thus allowing continuous contact of the electrode and the reactants at/near the interface. As a proof-of-concept, electrooxidative CÀH/NÀH coupling and electrooxidation of benzyl alcohol were shown to be accelerated by more than an order of magnitude as compared to the corresponding bulk reactions. The new electrochemical microreactor has unique features that allow i) voltage-controlled acceleration of electrochemical reactions by voltage-dependent formation of the interfacial microreactor; ii) "reversible" electrochemical derivatization; and iii) in situ mechanistic study and capture of key radical intermediates when coupled with mass spectrometry.

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“…22,23 In contrast to the previously described enclosed DART interfaces, the here presented setup introduces a nebulized stream of liquid into the confined ionization region and has already been successfully applied for the coupling of an electrochemical cell to DART-MS for real-time product analysis during electrochemical reactions. [24][25][26] This work provides deeper insights into the effects of various setup properties such as the enclosed interface, the spray chamber and the introduction system parameters on the analyte signal intensity, reproducibility and susceptibility to interferences from the surrounding. Furthermore, the universal applicability of the setup for the analysis of liquid sample streams is emphasized by demonstrating the coupling with HPLC during isocratic and gradient elution.…”

Section: Introductionmentioning

confidence: 99%

Implementation of an enclosed ionization interface for the analysis of liquid sample streams with direct analysis in real time mass spectrometry

Kloth

Khanipour

Mayrhofer

et al. 2021

Rapid Comm Mass Spectrometry

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Rationale:The development of an interface to introduce liquid sample streams to direct analysis in real time mass spectrometry (DART-MS) is of great interest for coupling various analytical techniques, using non-volatile salts, with MS. Therefore, we devised an enclosed ionization interface and a sample introduction system for the versatile analysis of liquid samples with DART-MS. Methods: The sample introduction system consists of a nebulizer, a spray chamber and a transfer line, while the confined ionization interface is created by implementing a cross-shaped housing between the ion source and the MS inlet. Methodical studies of the effects of various setup parameters on signal intensity and peak shape were conducted, while its diverse applicability was demonstrated by coupling with high-performance liquid chromatography (HPLC) for the analysis of alcohols, organic acids and furanic compounds. Results: The confinement of the ionization interface results in a robust setup design with a well-defined ionization region for focusing of the sprayed sample mist. Thereby, an increase in analyte signal intensity by three orders of magnitude and improved signal stability and reproducibility were obtained in comparison to a similar open ionization interface configuration. Additionally, the successful quantification of alcohols could be demonstrated as well as the compatibility of the setup with HPLC gradient elution. Conclusions: A versatile setup design for the analysis of liquid sample streams with DART-MS was devised for monitoring reactions or hyphenating analytics with MS. It minimizes This article is protected by copyright. All rights reserved.interferences from the laboratory surrounding as well as allows for safe handling of hazardous and toxic chemicals, which renders it suitable for a broad range of applications.

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Electrochemical Real‐Time Mass Spectrometry (EC‐RTMS): Monitoring Electrochemical Reaction Products in Real Time

Abstract: Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Cited by 66 publications

References 46 publications

Flow Electrolyzer Mass Spectrometry with a Gas‐Diffusion Electrode Design

Flow Electrolyzer Mass Spectrometry with a Gas‐Diffusion Electrode Design

Accelerating Electrochemical Reactions in a Voltage‐Controlled Interfacial Microreactor

Implementation of an enclosed ionization interface for the analysis of liquid sample streams with direct analysis in real time mass spectrometry

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