How Temperature Affects the Selectivity of the Electrochemical CO2 Reduction on Copper

Rafaël E Vos; Kees E Kolmeijer; Thimo S Jacobs; Ward van der Stam; Bert M Weckhuysen; Marc T M Koper

doi:10.1021/acscatal.3c00706

How Temperature Affects the Selectivity of the Electrochemical CO₂ Reduction on Copper

ACS Catal. 2023 Jun 1;13(12):8080-8091. doi: 10.1021/acscatal.3c00706. eCollection 2023 Jun 16.

Authors

Rafaël E Vos¹, Kees E Kolmeijer¹, Thimo S Jacobs², Ward van der Stam², Bert M Weckhuysen², Marc T M Koper¹

Affiliations

¹ Leiden Institute of Chemistry, Leiden University, P.O.Box 9502, 2300 RA Leiden, The Netherlands.
² Inorganic Chemistry and Catalysis group, Debye Institute for Nanomaterials Science and Institute for Sustainable and Circular Chemistry, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.

Abstract

Copper is a unique catalyst for the electrochemical CO₂ reduction reaction (CO2RR) as it can produce multi-carbon products, such as ethylene and propanol. As practical electrolyzers will likely operate at elevated temperatures, the effect of reaction temperature on the product distribution and activity of CO2RR on copper is important to elucidate. In this study, we have performed electrolysis experiments at different reaction temperatures and potentials. We show that there are two distinct temperature regimes. From 18 up to ∼48 °C, C2+ products are produced with higher Faradaic efficiency, while methane and formic acid selectivity decreases and hydrogen selectivity stays approximately constant. From 48 to 70 °C, it was found that HER dominates and the activity of CO2RR decreases. Moreover, the CO2RR products produced in this higher temperature range are mainly the C1 products, namely, CO and HCOOH. We argue that CO surface coverage, local pH, and kinetics play an important role in the lower-temperature regime, while the second regime appears most likely to be related to structural changes in the copper surface.