Jump to main content
Jump to site search

Issue 11, 2019
Previous Article Next Article

Modeling the electrical double layer to understand the reaction environment in a CO2 electrocatalytic system

Author affiliations

Abstract

The environment of a CO2 electroreduction (CO2ER) catalyst is intimately coupled with the surface reaction energetics and is therefore a critical aspect of the overall system performance. The immediate reaction environment of the electrocatalyst constitutes the electrical double layer (EDL) which extends a few nanometers into the electrolyte and screens the surface charge density. In this study, we resolve the species concentrations and potential profiles in the EDL of a CO2ER system by self-consistently solving the migration, diffusion and reaction phenomena using the generalized modified Poisson–Nernst–Planck (GMPNP) equations which include the effect of volume exclusion due to the solvated size of solution species. We demonstrate that the concentration of solvated cations builds at the outer Helmholtz plane (OHP) with increasing applied potential until the steric limit is reached. The formation of the EDL is expected to have important consequences for the transport of the CO2 molecule to the catalyst surface. The electric field in the EDL diminishes the pH in the first 5 nm from the OHP, with an accumulation of protons and a concomitant depletion of hydroxide ions. This is a considerable departure from the results obtained using reaction-diffusion models where migration is ignored. Finally, we use the GMPNP model to compare the nature of the EDL for different alkali metal cations to show the effect of solvated size and polarization of water on the resultant electric field. Our results establish the significance of the EDL and electrostatic forces in defining the local reaction environment of CO2 electrocatalysts.

Graphical abstract: Modeling the electrical double layer to understand the reaction environment in a CO2 electrocatalytic system

Back to tab navigation

Supplementary files

Publication details

The article was received on 02 Aug 2019, accepted on 01 Oct 2019 and first published on 01 Oct 2019


Article type: Paper
DOI: 10.1039/C9EE02485A
Energy Environ. Sci., 2019,12, 3380-3389
  • Open access: Creative Commons BY-NC license
  •   Request permissions

    Modeling the electrical double layer to understand the reaction environment in a CO2 electrocatalytic system

    D. Bohra, J. H. Chaudhry, T. Burdyny, E. A. Pidko and W. A. Smith, Energy Environ. Sci., 2019, 12, 3380
    DOI: 10.1039/C9EE02485A

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements