A superior mixed electron and carbonate-ion conducting metal-carbonate composite membrane for advanced flue-gas carbon capture

• Chemical dealloying produces fine structure of porous silver matrix.
• Use of H2 to sweep CO2 and O2 enhances flux and produces a pure stream of CO2 and H2O.
• Stable flux has been achieved over 900-h testing period.

Developing cost-effective, energy-efficient and CO2-selective advanced carbon capture technologies for carbon intensive flue gas is of vital importance to the reduction of carbon pollution and mitigation of global climate change. In the present work, we report that an electrochemistry-based mixed electron and carbonate-ion conducting metal-carbonate composite membrane with porous metal matrix fabricated by a chemical dealloying method exhibits superior CO2/O2 flux density and stability over a 900-h testing period. The results also demonstrate that the presence of H2 in the sweeping gas can significantly enhance the CO2 flux density as a result of increased gradient of chemical potential of oxygen and produce a pure stream of CO2 and H2O for easy downstream conversion. The fundamental mechanisms leading to the superior performance are also discussed.