Carboxysome-Inspired Electrocatalysis using Enzymes for the Reduction of CO at Low Concentrations.

The electrolysis of dilute CO streams suffers from low concentrations of dissolved substrate and its rapid depletion at the electrolyte-electrocatalyst interface. These limitations require first energy-intensive CO capture and concentration, before electrolyzers can achieve acceptable performances. For direct electrocatalytic CO 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 hydration kinetics and minimizes substrate depletion by making all dissolved carbon available for utilization, while a highly efficient formate dehydrogenase reduces CO cleanly to formate; down to even atmospheric concentrations of CO . This bio-inspired concept demonstrates that the carboxysome provides a viable blueprint for the reduction of low-concentration CO streams to chemicals by using all forms of dissolved carbon.