Abstract
Managing the gas–liquid interface within gas-diffusion electrodes (GDEs) is key to maintaining high product selectivities in carbon dioxide electroreduction. By screening silver-catalyzed GDEs over a range of applied current densities, an inverse correlation was observed between carbon monoxide selectivity and the electrochemical double-layer capacitance, a proxy for wetted electrode area. Plotting current-dependent performance as a function of cumulative charge led to data collapse onto a single sigmoidal curve indicating that the passage of faradaic current accelerates flooding. It was hypothesized that high cathode alkalinity, driven by both initial electrolyte conditions and cathode half-reactions, promotes carbonate formation and precipitation which, in turn, facilitates electrolyte permeation. This mechanism was reinforced by the observations that post-test GDEs retain less hydrophobicity than pristine materials and that water-rinsing and drying electrodes temporarily recovers peak selectivity. This knowledge offers an opportunity to design electrodes with greater carbonation tolerance to improve device longevity.
Original language | English |
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Pages (from-to) | 400-411 |
Number of pages | 12 |
Journal | ChemSusChem |
Volume | 13 |
Issue number | 2 |
Early online date | 17 Nov 2019 |
DOIs | |
Publication status | Published - 19 Jan 2020 |
Keywords
- carbon dioxide reduction
- electrochemistry
- energy conversion
- gas diffusion electrodes
- wetting