Electrochemical CO₂ Fixation and Release Cycle Featuring a Trinuclear Zinc Complex for Direct Air Capture

CO₂ capture technology can mitigate greenhouse gas emissions and global warming. CO₂ capture driven by electrochemical reactions is attractive because the operation is carried out at normal temperature and pressure and involves a simple input system using electrical energy. Although promising metal complexes with high CO₂ fixation performance have been reported, there are few studies on systems that combine electrochemical reactions and metal complexes. Here, we demonstrated stable CO₂ fixation-release cycles using an electrochemical system with trinuclear Zn(II) complex (Zn₃L) as the CO₂ fixative and an ionic liquid as a supporting electrolyte for the stable operation. This system showed a faster CO₂ fixation rate than that of an aqueous alkaline solution at the same concentration. Continuous release and refixation of CO₂ were achieved by decomposition and reconstruction of the complex structure induced by H⁺ and OH^- supplied from a bipolar membrane equipped in the electrolytic cell. The CO₂ fixation-release cycle was demonstrated even for dilute CO₂ (450 ppm) in air, where the CO₂ capture rate reached approximately 46 % of CO₂ contained in the air under an air flow condition of 200 mL ⋅ min^-1. This case, combining electrochemical drive and metal complexes, will provide a new option for CO₂ capture technology.