Carboxysome‐Inspired Electrocatalysis using Enzymes for the Reduction of CO ₂ at Low Concentrations**

Abstract

Abstract The electrolysis of dilute CO 2 streams suffers from low concentrations of dissolved substrate and its rapid depletion at the electrolyte‐electrocatalyst interface. These limitations require first energy‐intensive CO 2 capture and concentration, before electrolyzers can achieve acceptable performances. For direct electrocatalytic CO 2 reduction from low‐concentration sources, we introduce a strategy that mimics the carboxysome in cyanobacteria by utilizing microcompartments with nanoconfined enzymes in a porous electrode. A carbonic anhydrase accelerates CO 2 hydration kinetics and minimizes substrate depletion by making all dissolved carbon available for utilization, while a highly efficient formate dehydrogenase reduces CO 2 cleanly to formate; down to even atmospheric concentrations of CO 2 . This bio‐inspired concept demonstrates that the carboxysome provides a viable blueprint for the reduction of low‐concentration CO 2 streams to chemicals by using all forms of dissolved carbon.