The electroreduction of CO₂ (ERCO₂) into value-added products has recently gained recognition as one of the most promising strategies for CO₂ utilization from both economic and environmental perspectives. Research efforts have focused on developing catalysts, optimizing reactor designs, and refining operating conditions to improve the overall efficiency of the process. A novel and potentially transformative approach has emerged: the integration of external magnetic fields into electrochemical systems to enhance ERCO₂ performance. This strategy may significantly improve the scalability and industrial viability of the technology [1].

In this study, an initial experimental evaluation was conducted, targeting formate as the main product. A filter-press reactor with a gas diffusion electrode (GDE) cathode containing bismuth as the catalyst was employed. The system operated in a liquid-phase configuration, with a catholyte composed of 0.5 M KCl and 0.45 M KHCO₃, supplied at varying flow rates. Pure CO₂ was introduced at 200 mL min⁻¹, while the anode was fed with 1 M KOH. Magnets were placed near both the cathode and anode. Modeling showed that magnet placement significantly influenced the magnetic field strength: a single magnet near the anode produced a 20 mT field on the GDE, whereas placing two magnets at opposite reactor ends increased the field strength to 400 mT.

To explore the effect of magnetic fields on ERCO₂ performance, experiments were conducted at different catholyte flow rates (0.07, 0.15, and 0.57 mL min⁻¹ cm⁻²) while maintaining a constant current density of 200 mA cm⁻² [2]. The results demonstrated a clear enhancement in both formate concentration and Faradaic efficiency (FE) when a magnetic field was applied. Notably, the improvement was more pronounced at lower flow rates. At 0.07 mL min⁻¹ cm⁻², formate concentration increased from 18.05 to 27.25 g L⁻¹ (a 50% increase), while at 0.57 mL min⁻¹ cm⁻², the increase was approximately 20%. These improvements are attributed to the magnetohydrodynamic (MHD) effect induced by the magnetic field in the mass transfer layer between the GDE and the electrolyte. The MHD effect enhances fluid mixing and mass transport in the cathodic compartment, which is especially beneficial at low flow rates, where natural turbulence is limited.

Beyond formate production, the magnetic field-driven MHD effect presents opportunities to improve the formation of more complex products such as alcohols, methane, ethanol, and other multi-carbon (C₂+) compounds. Magnetic fields may also contribute to stabilizing key reaction intermediates, facilitating multi-electron transfer processes. Moreover, spin-related phenomena, such as the stabilization of radical pair states, should also be considered when evaluating the full impact of magnetic fields on ERCO₂ systems [1].

In summary, the integration of magnetic fields into ERCO₂ systems offers a promising route to enhance process efficiency and product selectivity. These findings represent a significant step toward the industrial implementation of electrochemical CO₂ conversion technologies.