Carboxysome‐inspired electrocatalysis using enzymes for the reduction of CO2 at low concentrations

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.