Reaction Pathways for Electrochemical CO2 Reduction into Ethanol

Electrochemical CO2 reduction reaction (CO2RR) offers a promising route to storing chemical energy and producing valuable chemicals, while also contributing to carbon cycle closure. Despite significant advances in electrocatalytic CO2RR for multi-carbon products, challenges remain in optimizing catalysts for high selectivity and efficiency. Cu-based heterogeneous catalysts are among the most promising options; however, enhancing their catalytic efficiency and product selectivity remains complex due to several factors. One key challenge is that product selectivity heavily depends on the catalyst’s surface morphology, which impacts both Faradaic efficiency and overpotential requirements for target product formation. Additionally, the reaction pathways and intermediates for multi-carbon products are not yet fully understood, complicating efforts to achieve consistent multi-carbon yields. Variability introduced by the electrolyte environment, applied potential, and operating conditions further impacts selectivity and efficiency. This review aims to address these challenges by exploring the interplay between the surface structure of Cu-based catalysts and system parameters that shape reaction pathways for ethanol formation. Notably, we explore alternative pathways beyond the conventional mechanisms involving CHO, COH, and CO dimers.