UC Berkeley

Pulsed electrolysis has been demonstrated to improve the faradaic efficiency (FE) to C2+ products during the electrochemical reduction of CO2 over a Cu catalyst, but the nature of this enhancement is poorly understood. Herein, we developed a time-dependent continuum model of pulsed CO2 electrolysis on Cu in 0.1 M CsHCO3 that faithfully represents the experimentally observed effects of pulsed electrolysis. This work shows that pulsing results in dynamic changes in the pH and CO2 concentration near the Cu surface, which lead to an enhanced C2+ FE as a consequence of repeatedly accessing a transient state of heightened pH and CO2 concentration at high cathodic overpotential. Using these insights, a variety of pulse shapes were explored to establish operating conditions that maximize the rate of C2+ product formation and minimize the rates of H2 and C1 product formation.