Mixed-matrix membranes for CO₂ separation: role of the third component

Mixed-matrix membranes (MMMs) have exhibited excellent performances for CO₂ separation, but it is still an ongoing challenge to enhance the separation performance through optimization of their structures. Recent studies demonstrated that the introduction of a tertiary component may play a positive role in improving the separation performance of two-component MMMs (polymer matrix and filler), showing great promise for addressing this challenge. Herein, recent advances in different types of tertiary components adopted in MMMs for CO₂ separation are reviewed, including small molecules, macromolecules, and porous materials, and a concise conclusion and outlook are outlined toward ternary MMM fabrication.