Nanoengineering membrane surfaces: A new paradigm for efficient CO₂ capture

Thin-film composite (TFC) membranes with superior separation properties for H₂/CO₂, CO₂/N₂, and CO₂/CH₄ are of great interest for CO₂ capture. As the selective layer of the membranes becomes thinner (∼100 nm or less) to enhance gas permeance, it can be surface-engineered to significantly improve gas separation properties. This paper aims to critically review scalable nanotechnologies adopted to modify membrane surfaces to improve CO₂ capture performance, including atomic layer deposition, chemical vapor deposition, plasma treatment, direct fluorination, ion/electron beam treatment, ozone treatment, and surface-initiated polymerization. We first describe the mechanisms of these nanotechnologies to achieve desired surface chemistries and nanostructures. Second, examples of surface-modified membranes with enhanced CO₂ capture performance are highlighted, and they are compared with state-of-the-art membranes to showcase their potential for gas separations. Finally, we summarize the pros and cons of these technologies to transform membrane technology for practical applications.