A new fuel cell system offers a route to electricity and hydrogen production along with carbon dioxide capture. The Hybrid Na-CO₂ system developed in a collaboration between Georgia Institute of Technology and Ulsan National Institute of Science and Technology (UNIST) includes a step for CO₂ dissolution in aqueous solution.Schematic illustration of the hybrid Na-CO2 system and its reaction mechanism. Source: UNIST

The process increases the acidity of the solution, inducing an electrochemical reaction by increasing the number of protons, thereby increasing the potential to attract electrons. The fuel cell system includes a sodium metal cathode submerged in an organic electrolyte, a separation membrane consisting of a sodium super ionic conductor ceramic and a catalytic platinum anode in an aqueous electrolyte.

Injecting CO₂ into the water triggers a reaction that liberates gaseous hydrogen at the cathode – and produces an electric current. Sodium ions released by the anode pass through the membrane and recombine with the hydrogen carbonate ions formed by the dissolution of the gas. The system’s CO₂ conversion efficiency is 50 percent.

System stability was demonstrated by continuously producing gas-phase hydrogen during discharge for over 1,000 hours without damaging the electrode.

The research is published in iScience.