(670d) Coupling Microkinetics with Continuum Transport Models to Understand Electrochemical CO2 Reduction

Electrochemical CO2 reduction (eCO2R) is a promising approach for the sustainable production of fuels and chemicals using renewable electricity. Significant progress has been made over the past decade both from a modeling and experimental standpoint on understanding how several factors including the electrode material, electrolyte pH, CO2 availability and mass transport affect the reaction rate and efficiency for eCO2R. However, we are still faced with a number of challenges that have to be overcome to enable commercialization of CO2 electrolyzers.[1] In this regard, resolving the reaction environment at the vicinity of the electrode can provide crucial insights into the reaction mechanism and key parameters that control the electrolyzer performance.[2,3] In this work, we present a multi-scale approach that couples ab-initio microkinetic simulations to continuum transport models to understand eCO2R on Au in a flow reactor configuration. We find the simulated CO2 concentrations, pH, the current density towards CO and the Tafel slopes all strongly depend on both the applied potential and the spatial distance along the electrode. We further analyze the implications of the spatial distribution of these parameters and provide strategies to improve CO₂ utilization and the overall electrolyzer performance. Our work highlights the need to develop multidimensional, multiscale modeling approaches to capture the full complexity of the reaction environment at the vicinity of the electrode and obtain detailed understanding of eCO2R.

This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory (LLNL) under contract DE-AC52-07NA27344.

References:
[1] I. E. L. Stephens, K. Chan, et al., Journal of Physics:Energy, 4 (2023)
[2] S. Ringe, C. G. Morales-Guio, L. D. Chen, M. Fields, T. F. Jaramillo, C. Hahn, and K. Chan, Nature Communications 11 (2020)
[3] D. Bohra, J. H. Chaudhry, T. Burdyny, E. A. Pidko, and W. A. Smith, Energy & Environmental Science 12 (2019)