Quantification of water transport in a CO2 electrolyzer

Wheeler, Danika G.; Mowbray, Benjamin A. W.; Reyes, Angelica; Habibzadeh, Faezeh; He, Jingfu; Berlinguette, Curtis P.

doi:10.1039/d0ee02219e

Cited by 123 publications

(170 citation statements)

References 37 publications

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“…We also envisage that the water concentration at the catalyst surface (reaction interface) would always be > 0 and does not vary significantly based on the relative humidity measurements in our tests at the inlet and outlet of the reactor (R.H of 75% at inlet and 79% at outlet). This result is in agreement with a recent study on water quantification in a MEA where in-situ humidity measurements were performed during CO2 electroreduction to confirm that the water concentration at the catalyst surface (membrane-GDE interface) remains constant regardless of the humidity level at the inlet CO2 stream 29 .…”

Section: Predicted Spatial and Average Faradaic Efficiencysupporting

confidence: 92%

Spatial reactant distribution in CO2 electrolysis: Balancing CO2 utilization and Faradaic Efficiency

Subramanian

Middelkoop

Burdyny

2021

Preprint

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The production of value added C1 and C2 compounds within CO2 electrolyzers has reached sufficient catalytic performance that system and process performance – such as CO2 utilization – have come more into consideration. Efforts to assess the limitations of CO2 conversion and crossover within electrochemical systems have been performed, providing valuable information to position CO2 electrolyzers within a larger process. Currently missing, however, is a clear elucidation of the inevitable trade-offs that exist between CO2 utilization and electrolyzer performance, specifically how the Faradaic Efficiency of a system varies with CO2 availability. Such information is needed to properly assess the viability of the technology. In this work, we provide a combined experimental and 3D modelling assessment of the trade-offs between CO2 utilization and selectivity at 200 mA/cm2 within a membrane-electrode assembly CO2 electrolyzer. Using varying inlet flow rates we demonstrate that the variation in spatial concentration of CO2 leads to spatial variations in Faradaic Efficiency that cannot be captured using common ‘black box’ measurement procedures. Specifically, losses of Faradaic efficiency are observed to occur even at incomplete CO2 consumption (80%). Modelling of the gas channel and diffusion layers indicated at least a portion of the H2 generated is considered as avoidable by proper flow field design and modification. The combined work allows for a spatially resolved interpretation of product selectivity occurring inside the reactor, providing the foundation for design rules in balancing CO2 utilization and device performance in both lab and scaled applications.

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Section: Predicted Spatial and Average Faradaic Efficiencysupporting

confidence: 92%

Spatial reactant distribution in CO2 electrolysis: Balancing CO2 utilization and Faradaic Efficiency

Subramanian

Middelkoop

Burdyny

2021

Preprint

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“…After longer operation of a zero-gap electrolyzer cell ( Fig. 1a , Supplementary Figure 1 ) with alkaline anolyte, salt precipitates at the cathode, gradually decreasing its performance 24 , 25 , 29 . We also experienced this phenomenon ( Supplementary Note 1 ), in the form of continuous product formation current decrease ( Supplementary Figure 2a ) and/or pressure build-up.…”

Section: Performance Fading Due To Precipitate Formationmentioning

confidence: 99%

“…1b ), and the consequent precipitate formation and performance fading still occur (see Supplementary Figure 6 and discussion therein). Increasing the humidity of the CO 2 gas stream is another alternative mitigation strategy, but it changes the overall operation of the cell 24 , 29 . An elegant solution to this problem would be to operate such electrolyzer cells with pure water anolyte, inherently preventing precipitate formation in the cathode GDE.…”

Section: Performance Fading Due To Precipitate Formationmentioning

confidence: 99%

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Operando cathode activation with alkali metal cations for high current density operation of water-fed zero-gap carbon dioxide electrolysers

et al. 2021

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“…42 Based on this result, we sought to further improve convective mass transfer in the cathode compartment using different flow pattern geometries (interdigitated, serpentine, and parallel; Figure 4a). These flow plates were 3D printed using an acrylonitrile butadiene styrene (ABS) plastic, coated with silver paint to improve conductivity (Figure S12), 43 and tested in the electrolyzer with the foam electrode (Figure 4b). The electrolyzer with the interdigitated flow pattern exhibited the highest FE CO values (69 ± 4% FE CO at 100 mA cm -2 ) of the flow plates tested, without any additional voltage or pressure drop penalty (Figures 4b, S13, S14).…”

Section: Effect Of Convective Mass Transfer and Flow Plate Design On Bicarbonate Electrolysismentioning

confidence: 99%

Metallic Porous Electrodes Enable Efficient Bicarbonate Electrolysis

Zhang

Lees²,

Salvatore³

et al. 2021

Preprint

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We demonstrate here that a porous free-standing silver foam cathode in an electrolytic flow electrolyzer mediates efficient electrolysis of 3.0 M bicarbonate solutions into CO. These results have direct implications for carbon capture schemes where OH- solutions react with CO2 to form bicarbonate-rich solutions that need to be treated to recycle the sorbent and recover the CO2. Our study shows a viable path for replacing the high-temperature thermal process currently used to recover CO2 from these carboncapture solutions by using electricity to drive the conversion of bicarbonate into CO2 and subsequently into CO. The use of free-standing porous silver electrodes was found to yield electrolysis performance parameters (e.g., a Faradaic efficiency for CO production, FECO, of 95% at 100 mA cm2; <3% performance loss after 80 h operation) that are superior to results obtained in bicarbonate electrolyzers that utilize conventional carbon-based gas diffusion electrodes (GDEs) designed for gaseous CO2 fed electrolyzers. This liquid-fed bicarbonate electrolyzer achieves high CO formation rates with the added benefit of not requiring an energy-intensive CO2 regeneration step that would be necessary for the electrolysis of gaseous CO2. These findings represent a potentially important step in closing the carbon cycle.

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Quantification of water transport in a CO₂ electrolyzer

Abstract: The distribution and flow of water in a CO2 electrolyzer can be defined at variable operating conditions using a 3D model coupled with an analytical electrolyzer.

Cited by 123 publications

References 37 publications

Spatial reactant distribution in CO2 electrolysis: Balancing CO2 utilization and Faradaic Efficiency

Spatial reactant distribution in CO2 electrolysis: Balancing CO2 utilization and Faradaic Efficiency

Operando cathode activation with alkali metal cations for high current density operation of water-fed zero-gap carbon dioxide electrolysers

Metallic Porous Electrodes Enable Efficient Bicarbonate Electrolysis

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