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Abstract 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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Hydrophilic or Hydrophobic? Optimizing the Catalyst Microenvironment for Gas‐Involving Electrocatalysis
Abstract Electrocatalysis plays a key role in the development of renewable energy technologies. Along with the design of electrocatalysts, the microenvironment around catalytic sites has received increasing attention because it affects the distribution and mass transport of reaction species and impacts the reaction kinetics. In this Concept article, we highlight some mechanistic insights into the effect of microenvironment on gas‐involving electrocatalytic reactions, including CO2reduction, 2‐electron oxygen reduction, and hydrazine oxidation, demonstrating their sensitivity to the wetting properties of microenvironment. For reactions with a gaseous reactant, a moderately hydrophobic microenvironment can greatly enhance the mass transport of gaseous species to accelerate the reaction kinetics while improving the stability of gas‐diffusion electrodes. In contrast, for reactions with a liquid reactant and gaseous product, a hydrophilic microenvironment improves the exposure of catalytic sites to the reactant, while a hydrophobic microenvironment benefits the reaction on the other end by accelerating the diffusion and detachment of generated gas bubbles, which would otherwise block the catalytic sites from the reactant. These understandings and insights can provide important guidelines on the control and optimization of catalyst microenvironment for the development of efficient electrolyzers.
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- Award ID(s):
- 1943732
- PAR ID:
- 10487025
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemCatChem
- Volume:
- 16
- Issue:
- 8
- ISSN:
- 1867-3880
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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