(632d) Magnetic Field Assisted Electrochemical Transformation of CO2 into Value-Added Products

Reducing greenhouse gas emissions is a major international priority to avoid the effects of climate change. Electrochemical CO₂ reduction (ERCO₂) offers a path to simultaneously address the CO₂ emissions and the production of chemicals that can enable the storage of renewable energy in the form of liquid fuels, addressing energy storage challenges. Nevertheless, ERCO₂ has been associated with several shortcomings that compromise its feasible applicability. Coupling magnetic fields with ERCO₂ has emerged as a novel, effective strategy for boosting process performance [1,2]. However, understanding the physics behind magneto-electrochemistry is limited, and a deep study of magnetic field configurations driving process enhancement is lacking. This study evaluates the impact of magnetic fields on ERCO₂ to formic acid within a gas diffusion electrode (GDE) flow cell operating at commercially relevant conditions [3]. We observed that placing magnets near the cathode or at both ends of the cell boosted formate concentration by more than 20%, achieving values of 4.4 gL⁻¹ and 4.95 gL⁻¹, respectively, with Faradaic efficiencies approaching 100%. These improvements are attributed to the magnetohydrodynamic (MHD) effect, which enhances mass transfer by inducing turbulence in the cathodic electrolyte. This effect was particularly important at low catholyte flow rates, leading to a more than 50 % increase in formate concentration, reaching up to 27.25 gL^-1 at a flow rate of 0.07 mLmin^-1cm^-2. However, the application of magnetic fields also increased energy consumption due to the higher cell voltage requirements, as indicated by our Tafel analysis. Despite this limitation, this study demonstrates the potential application of magnetic fields to enhance ERCO₂ processes, paving the way for future research to further explore and optimize this promising strategy.

[1] C. González-Fernández, G. Díaz-Sainz, A. Gutierrez-Carballo, E. Bringas, I. Ortiz, G.G. Botte, J. Gomez-Pastora, Perspectives of Magnetically Enhanced Electroconversion of CO2 to Formic Acid and Formate, ACS Sustain Chem Eng 12 (2024) 3390–3401.

[2] S. Luo, K. Elouarzaki, Z.J. Xu, Electrochemistry in Magnetic Fields, Angewandte Chemie - International Edition 61 (2022) e202203564.

[3] J.A. Abarca, X. Wu, C. González-Fernández, I.H. Karampelas, A. Gutierrez-Carballo, J.A. Gauthier, G.G. Botte, J. Solla-Gullon, G. Díaz-Sainz, A. Irabien, J. Gomez-Pastora. Magnetically enhanced electrochemical conversion of CO2 to formate: Experimental studies. Chemical Engineering Journal (under review).