Capture and conversion of CO 2 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 CO 2 reduction (CO 2 R) cell to capture and convert CO 2 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 CO 2 at an electrochemical energy consumption of 155.4 kJ mol −1 or 0.98 kWh kg −1 of CO 2 and a CO 2 capture efficiency of 71%. The direct coupled, vapor-fed CO 2 R cell yields a total Faradaic efficiency of up to 95% for electrochemical CO 2 reduction to CO. The proof-of-concept system provides a unique technological pathway for CO 2 capture and conversion from oceanwater with only electrochemical processes.
Solar-driven reduction of carbon dioxide represents a carbon neutral pathway for the synthesis of fuels and chemicals. We report here results for solar-driven CO 2 reduction using a gas diffusion electrode (GDE) directly powered by a photovoltaic cell. A GaInP/GaInAs/Ge triple junction photovoltaic cell was used to power a reverse-assembled gas diffusion electrode employing a Ag nanoparticle catalyst layer. The device had a solar-to-CO energy conversion efficiency of 19.1 % under simulated AM 1.5G illumination at 1 Sun. The use of a reverseassembled GDE prevented transition from a wetted to a flooded catalyst bed and allowed the device to operate stably for >150 h with no loss in efficiency. Outdoor measurements were performed under ambient solar illumination in Pasadena, CA, resulting in a peak solar-to-CO efficiency 18.7 % with a CO production rate of 47 mgcm-2 per day and a diurnal-averaged solar to fuel conversion efficiency of 5.8 %.
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