A direct coupled electrochemical system for capture and conversion of CO₂ from oceanwater

Capture and conversion of CO₂ from oceanwater can lead to net-negative emissions and can provide carbon source for synthetic fuels and chemical feedstocks at the gigaton per year scale. Here, we report a direct coupled, proof-of-concept electrochemical system that uses a bipolar membrane electrodialysis (BPMED) cell and a vapor-fed CO₂ reduction (CO₂R) cell to capture and convert CO₂ from oceanwater. The BPMED cell replaces the commonly used water-splitting reaction with one-electron, reversible redox couples at the electrodes and demonstrates the ability to capture CO₂ at an electrochemical energy consumption of 155.4 kJ mol^-1 or 0.98 kWh kg^-1 of CO₂ and a CO₂ capture efficiency of 71%. The direct coupled, vapor-fed CO₂R cell yields a total Faradaic efficiency of up to 95% for electrochemical CO₂ reduction to CO. The proof-of-concept system provides a unique technological pathway for CO₂ capture and conversion from oceanwater with only electrochemical processes.