Bipotentiostatic tandem electrocatalysis of the CO2 reduction reaction yielding C2+ fuels

Abstract

Electrochemical CO₂ conversion to fuel molecules is an attractive strategy towards atmospheric carbon attenuation. In the fuel conversion catalysis of carbon dioxide, surface adsorbed CO was often identified as a key intermediate, and the inherently low concentration of which has recently been highlighted as an important factor in the low yields of C₂₊ fuels. Here a bipotentiostatic tandem catalysis system was designed such that the loads for electrosynthesis of CO from CO₂ and the subsequent C–C coupling reaction were split to two separate working electrodes with independent potential programming. Coulometric tracking of the reaction indicated efficient turnover of the electrosynthetic CO to fuel molecules at the second working electrode, achieving a high C₂₊ yield of 67.3% and a 6.5% faradaic efficiency towards 1-propanol. Importantly, the unique capability of the tandem catalysis system allowed control of the CO flux to the second working electrode, which enabled the direct quantification of the C–C coupling turnover frequency on a surface copper atom (0.43 ± 0.06 s⁻¹), when the reaction current was electrode-kinetics controlled with sufficient CO mass transport. Furthermore, the bipotentiostatic reaction platform developed here exhibits modular tunability, such that the expansion of the platform to other sequential electrocatalyses is imaginable.