Carboxysome-Inspired Electrocatalysis using Enzymes for the Reduction of CO2 at Low Concentrations

Abstract

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 introduce a strategy that mimics the carboxysome in cyanobacteria by utilizing microcompartments with nanoconfined enzymes in a porous electrode. A carbonic anhydrase accelerates CO₂ hydration kinetics and minimizes substrate depletion by making all dissolved 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 for the reduction of low-concentration CO₂ streams to chemicals by using all forms of dissolved carbon.

Keywords: Carbon Dioxide Reduction; Electrochemistry; Enzyme Catalysis; Metalloenzymes; Protein Film Electrochemistry.