Experimental Parameters Influencing Hydrocarbon Selectivity during the Electrochemical Conversion of CO2

The selectivity of the products formed from the electrochemical conversion of CO2 can be controllably altered by changing the experimental conditions while the catalyst surface is kept the same. Herein, we demonstrate the importance of controlling electrolysis conditions and reporting detailed experimental parameters, such that catalyst activity can be compared objectively, which will aid in our understanding of the complex CO2-reaction processes reported across various research groups. In this work, we report that selectivity toward C2H4 and CO is favored when the kinetics of CO2 equilibration is made faster. Also, local surface pH can be altered by manipulating either buffer capacity or the Nernst-layer thickness; a more acidic surface favors the formation of CH4 and HCOOH on electropolished Cu surfaces, whereas a more basic surface favors C2H4 formation.