Using a 3D Porous Flow-Through Electrode Geometry for High-Rate Electrochemical Reduction of CO₂ to CO in Ionic Liquid

Journal Article · Fri Oct 11 00:00:00 EDT 2019 · ACS Catalysis

DOI:https://doi.org/10.1021/acscatal.9b03201· OSTI ID:1630811

Vedharathinam, Vedasri ^[1]; Qi, Zhen ^[1]; Horwood, Corie  ^[1]; Bourcier, Bill ^[1]; Stadermann, Michael ^[1]; Biener, Juergen ^[1]; Biener, Monika  ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Three-dimensional porous flow-through electrodes promise the realization of higher current densities in the electrochemical carbon dioxide reduction reaction (CO₂RR) by overcoming mass-transport limitations associated with the diffusion of dissolved CO₂ in the bulk electrolyte. Using an ionic-liquid-based electrolyte, [EMIM]BF₄, offers the additional benefit of higher CO₂ solubility compared to water-based electrolytes. Here, we quantitatively evaluated the effects of flow-driven reactant transport on electrode activity and selectivity for the electrochemical CO₂RR in [EMIM]BF4. High-surface-area porous flow-through electrodes were fabricated by wet-chemical deposition of Ag nanoflowers on commercial macroporous Al foams. At the highest electrolyte flow-through rate of 100 mL min^–1, we observed a 70-fold increase in partial CO current density, and a 7-fold increase in the Faradaic efficiency toward CO, from 10% without flow to 75% with flow. At the same time, the selectivity changed from oxalate as the main product without flow to CO in the electrolyte flow-through configuration. These results demonstrate that the flow-through approach provides a promising path forward to control selectivity and to overcome mass-transport limitations of the electrochemical CO₂RR.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1630811
• Report Number(s): LLNL-JRNL-782157; 976694
• Journal Information: ACS Catalysis, Vol. 9, Issue 12; ISSN 2155-5435
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
flow-through electrochemistry
ionic liquid
CO2 reduction
porous electrode