Toward Complete CO2 Electroconversion: Status, Challenges, and Perspectives

Electrocatalytic conversion of carbon dioxide (CO₂) into valuable carbon-based fuels and chemicals represents a promising approach to closing the carbon cycle and setting a circular economy. Nevertheless, for current electrocatalytic CO₂ reduction reaction (ECO₂RR) systems, realizing 100% CO₂ conversion with simultaneously high overall CO₂ conversion rate (i.e., single-pass conversion) and high Faradaic efficiency (FE) remains a significant challenge. Enhancing CO₂ conversion rate often results in a decrease in FE, conversely, improving FE may limit the CO₂ conversion rate. Metal–CO₂ (M–CO₂) batteries with CO₂ conversion functions face similar challenges, particularly for reversible M–CO₂ batteries, which do not accomplish net CO₂ reduction because nearly all of CO₂RR products are reoxidized to CO₂ during subsequent charging process. Such electrocatalytic CO₂ conversion system for carbon neutrality poses substantial challenges. This perspective provides an in-depth analysis of state-of-the-art ECO₂RR systems and M–CO₂ batteries, alongside the main strategies employed to address their respective challenges. The critical importance of achieving both a high CO₂ conversion rate and high Faradaic efficiency is underscored for practical applications and to effectively close the carbon cycle. Furthermore, a strategic roadmap that outlines future research directions is presented, thereby facilitating the advancement of comprehensive CO₂ electroconversion technologies.