Strategies for breaking molecular scaling relationships for the electrochemical CO2 reduction reaction

Abstract

The electrocatalytic CO₂ reduction reaction (CO₂RR) is a promising strategy for converting CO₂ to fuels and value-added chemicals using renewable energy sources. Molecular electrocatalysts show promise for the selective conversion of CO₂ to single products with catalytic activity that can be tuned through synthetic structure modifications. However, for the CO₂RR by traditional molecular catalysts, beneficial decreases in overpotentials are usually correlated with detrimental decreases in catalytic activity. This correlation is sometimes referred to as a “molecular scaling relationship”. Overcoming this inverse correlation between activity and effective overpotential remains a challenge when designing new, efficient molecular catalyst systems. In this perspective, we discuss some of the concepts that give rise to the molecular scaling relationships in the CO₂RR by molecular catalysts. We then provide an overview of some reported strategies from the last decade for breaking these scaling relationships. We end by discussing strategies and progress in our own research designing efficient molecular catalysts with redox-active ligands that show high activity at low effective overpotentials for the CO₂RR.