Remarkable O2 permeation through a mixed conducting carbon capture membrane functionalized by atomic layer deposition

Abstract

The development of energy-efficient and cost-competitive carbon capture technology is of vital importance to effective reduction of carbon emissions and mitigation of global climate change. The present work reports that a highly energy-efficient electrochemical carbon capture membrane consisting of a carbonate and silver phase exhibits a remarkably high rate of O₂ permeation after the silver phase is functionalized with a nanoscale layer of Al₂O₃ by atomic layer deposition. The resulting permeation flux ratio of O₂ to CO₂ was 1.5 : 1, a complete reversal from 1 : 2 of the conventional membrane. The mechanisms of this exceptionally high rate of O₂ permeation were investigated by in situ Raman spectroscopy and theoretical DFT calculations. The results revealed that LiCO₄⁻ as the active surface species was responsible for the enhanced O₂ permeation. A new CO₂/O₂ transport model based on a “cogwheel” migration mechanism of CO₄²⁻ was presented to explain the experimental results with excellent agreement.