Paired electrosynthesis design strategy for sustainable CO2 conversion and product upgrading

CO2 electrolysis technology powered by renewable electricity is a sustainable strategy to reduce anthropogenic carbon emissions while producing valuable chemicals. Unfortunately, compared with CO2 reduction reaction (CO2RR) in cathode, the sluggish-kinetics and low value-added product (i.e., O2) of anodic oxygen evolution reaction (OER) during CO2 electrolysis will seriously drag down the whole efficiency and economic benefits. Alternatively, replacing OER with some thermodynamically more favorable oxidation reactions is promising to reduce energy input while producing high value-added products. Therefore, coupling CO2RR with these oxidation reactions to construct paired electrosynthesis systems is more meaningful for future applications, which has gained some far-reaching achievements in recent years. In this review, we summarize recent progress in construction of paired electrosynthesis systems involving CO2RR and propose possible future research directions. We start with fundamentals about traditional CO2 electrolysis. Then we propose the definition and classification of paired electrolysis, especially those involving CO2RR. Subsequently, we emphatically discuss the selection of various oxidation reactions coupled with CO2RR in the proposed paired electrolysis systems. Finally, from our point of view, the current challenges and corresponding perspectives on the development of paired electrolysis involving CO2RR are presented to inspire possible future research directions.