Dynamic Boundary Layer Simulation of Pulsed CO₂ Electrolysis on a Copper Catalyst

Pulsed electrolysis has been demonstrated to improve the faradaic efficiency (FE) to C<sub>2+</sub> products during the electrochemical reduction of CO<sub>2</sub> over a Cu catalyst, but the nature of this enhancement is poorly understood. Herein, we developed a time-dependent continuum model of pulsed CO<sub>2</sub> electrolysis on Cu in 0.1 M CsHCO<sub>3</sub> that faithfully represents the experimentally observed effects of pulsed electrolysis. This work shows that pulsing results in dynamic changes in the pH and CO<sub>2</sub> concentration near the Cu surface, which lead to an enhanced C<sub>2+</sub> FE as a consequence of repeatedly accessing a transient state of heightened pH and CO<sub>2</sub> concentration at high cathodic overpotential. Using these insights, a variety of pulse shapes were explored to establish operating conditions that maximize the rate of C<sub>2+</sub> product formation and minimize the rates of H<sub>2</sub> and C<sub>1</sub> product formation.