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

The electrolysis of dilute CO2 streams suffers from low concentrations of dissolved substrate and its rapid depletion at the electrolyte-electrocatalyst interface. These limitations require first energy-intensive CO2 capture and concentration, before electrolyzers can achieve acceptable performances. For direct electrocatalytic CO2 reduction from low-concentration sources, we in-troduce a strategy that mimics the carboxysome in cyanobacteria by utilizing microcompart-ments with nanoconfined and concentrated enzymes in a porous electrode. A carbonic anhy-drase accelerates CO2 hydration kinetics and minimizes substrate depletion by making all dis-solved carbon available for utilization, while a highly efficient formate dehydrogenase reduces CO2 cleanly to formate; down to even atmospheric concentrations of CO2. This bio-inspired concept demonstrates that the carboxysome provides a viable blueprint and strategy to achieve the reduction of low-concentration CO2 streams to chemicals.