Molecular copper catalysts for electro-reductive homocoupling of CO2 towards C2 compounds

Abstract

The electrochemical CO₂ reduction reaction (eCO₂RR) to multi-carbon products holds the potential to generate valuable building blocks for production of chemicals using renewable electricity, thereby diminishing the dependence on fossil feedstocks. The crucial mechanistic step in this process involves the electrochemical C–C coupling, primarily taking place on metallic Cu surfaces. However, these metallic surfaces pose mechanistic unclarities due to their structural complexity, leading to intricate mechanistic paths and difficulties in identifying the genuine catalytically active sites. In contrast, molecular catalysts with well-defined structures may offer distinctive active sites for the reaction, although their utilization remains relatively unexplored. Recent advancements in Cu-based organometallic structures have demonstrated significant potential for eCO₂RR, particularly in C–C coupling toward C₂ products such as C₂H₄ and C₂H₅OH. These developments are summarized and discussed herein, both in terms of catalyst development and mechanistic understanding.