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.

Ibadillah A. Digdaya, Ian Sullivan, Meng Lin, Lihao Han, Wen-Hui Cheng, Harry A. Atwater, Chengxiang Xiang