Fast electrochemical CO2 transport through a dense metal-carbonate membrane: A new mechanistic insight

We here report a mechanistic investigation into the electrochemical transport of CO2 through a dense metal-carbonate membrane. The investigation studied a total of six possible charge-transfer mechanisms involving CO32−, O22−, O2−, CO42− and CO52− as the active surface species, and derived the corresponding flux equation from each mechanism. The experimental CO2 flux densities measured under a range of chemical gradients were used to verify each mechanism by plotting the flux density against the corresponding flux expression of each mechanism. The results showed that CO42− scheme is the best mechanism to describe the electrochemical CO2 transport through the metal-carbonate membranes. A new transport model was also shown to describe the CO42− migration and charge-transfer.