Electrode Surface Heating with Organic Films Improves CO2 Reduction Kinetics on Copper

Management of the electrode surface temperature is an understudied aspect of (photo)electrode reactor design in both fundamental studies and optimized systems for complex reactions such as CO2 reduction. In this work, we study the impact of local electrode heating on electrochemical CO2 reduction. Using the ferri/ferrocyanide open circuit voltage as a reporter of the effective reaction temperature, we reveal how the interplay of surface heating and convective cooling poses a challenge for co-optimizing mass transport and thermal assistance of electrochemical reactions, where we focus on reduction of CO2 to carbon-coupled (C2+) products. The introduction of an organic coating on the electrode surface facilitates well-behaved electrokinetics with near-ambient bulk electrolyte temperature, enabling the discovery that surface heating to 60 °C decreases the voltage required for peak C2+ performance by ca. 100 mV compared to ambient conditions. This approach to thermal management offers a new dimension to electrochemical systems design. It moreover offers the opportunity to further probe thermal effects in electrochemical reactions, as demonstrated through Bayesian inference of Butler-Volmer kinetic parameters from a suite of high throughput experiments.