Pulsed Electrolysis Promotes CO ₂ Electroreduction to Multicarbon Products by Suppressing Electrolyte Flooding

Abstract

Abstract Electrochemical CO 2 reduction (CO 2 RR) converts CO 2 into value‐added fuels and chemicals using renewable electricity. Pulsed CO 2 RR(p‐CO 2 RR) has been proposed to enhance the selectivity of multicarbon products (C 2+ ), yet mechanistic clarity at industrially relevant rates remains limited by the complex gas–liquid–solid microenvironment of gas‐diffusion electrodes (GDEs). Here, we investigate p‐CO 2 RR in GDE flow‐cells operating at industrially‐relevant current densities. Under cathodic potentials where conventional constant‐potential CO 2 electrolysis yields > 70% H 2 (Faradaic efficiency, FE), pulsed operation achieves a maximum C 2+ FE of 82.7% at current densities above 0.4 A cm −2 . Operando Raman and UV–visible spectroscopy indicates that formation of Cu x O only weakly perturbs the coverage of *CO intermediates, suggesting that redox restructuring is not the principal driver of pulse‐enhanced C 2+ production. Instead, ex situ scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDS) mapping reveals a strong correlation between reduced electrolyte intrusion and improved C 2+ selectivity, with pulsing stabilizing the gas–liquid interface, suppressing electrolyte penetration, and enhancing CO 2 mass transfer. These experimental findings are supported by numerical simulations of electrochemical capillary‐pressure dynamics, which confirm that alternating cathodic and anodic potentials modulate interfacial wettability to retard flooding. These mechanistic insights contribute to the design principles for industrial p‐CO 2 RR systems, emphasizing hydrodynamic management over traditional catalyst engineering approaches.