Design of Highly Efficient Nanomembranes Toward Direct Air Capture. Essential Role of Nanolayer Interface

Abstract The role of membrane technology is growing in mitigation of global warming via direct capture of CO₂ from the atmosphere (DAC). Yet achieving both high permeability and selectivity remains challenging. In this study, the development of free‐standing, nanometer‐thick membranes is presented that are composed of layers of poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) (PEG). These nanomembranes are prepared by sequential spin coating of the precursor polymer solution and the subsequent radical cross‐linking. Addition of carbon nanotube or cellulose nanofiber enhanced physical stability of the nanomembrane. One of those nanomembranes exhibited record‐breaking CO₂ permeability (>10 000 GPU) and CO₂/N₂ selectivity (>50) at ambient conditions. This gas permeation is a kinetic process, and interface‐ controlled. This study offers a new design paradigm for highly efficient CO₂ separation.