Pulsing the Applied Potential in Electrochemical CO₂ Reduction Enhances the C₂ Activity by Modulating the Dynamic Competitive Binding of *CO and *H

Abstract

We explore dynamic electrocatalysis by pulsing the applied potential to modulate the temporal microenvironment during the electrochemical reduction of CO 2 . We focus on copper electrodes by virtue of their unique ability to bind *CO intermediates and enable C−C coupling to form high-value C 2 products, such as ethylene or ethanol. We examine the well-known competition between *CO and *H for active sites, as their relative coverage is crucial for enhancing the formation of C 2 products. We found that pulsing the applied potential can significantly enhance the electrocatalytic activity of C−C coupling, increasing the turnover frequency of C 2 products by up to 33-fold compared to potentiostatic electrolysis. We interpret this improvement in the context of oscillating surface coverage and the transient dynamics of the *CO/*H coverage during the cathodic pulse. Through a combination of experimental and computational methods, we investigate how pulse frequency influences the turnover frequency of CO 2 to C 2 products on Cu. Our study not only validates recent theoretical predictions about the potential of dynamic (electro)catalysis to surpass the limitations imposed by the Sabatier limit but also uncovers scientific and mechanistic insights into dynamic processes within the electrical double layer. These insights are instrumental in formulating design principles for pulsed CO 2 electrolysis with enhanced C 2 activity. The outcomes of this study lay a foundational framework for future advances in programmable CO 2 electrolysis with improved activity, selectivity, and durability.

Recent advances in dynamic reconstruction of electrocatalysts for carbon dioxide reduction

“… 135 Consequently, the surface dynamics can be modified by local reaction environment through pulsed electrolysis that regulate of concentration of H + , OH − ions and the coverage CO or carbonate, resulting in the changeable of CO 2 RR selectivity. 136 , 137 , 138 …”