Polymer Layer-Accelerated CO<sub>2</sub> Absorption\nin Aqueous Amino Acid Solutions

Direct\nair capture (DAC) of CO<sub>2</sub> via solvent-based absorption\nis considered a promising negative-emission technology. However, the\nlow concentration of CO<sub>2</sub> in the air and slow transport\ninto the solvent make DAC notoriously challenging to implement without\ncostly investments. In this study, we explore the fundamental role\nthat the bulk and surface properties of CO<sub>2</sub>-permeable polymer\nmembranes play in enhancing the efficiency of the solution sorption\nprocess in passive DAC of CO<sub>2</sub>. This work leverages various\nspectroscopic and computational studies to demonstrate that a hybrid\nsystem, comprising a reusable CO<sub>2</sub>-permeable polymer layer\nplaced atop an aqueous amino acid (AA) solution, can outperform a\npure aqueous AA system by 2-fold. We show how the enhanced solubility\nof CO<sub>2</sub> in the polymer layer can improve the transport of\nCO<sub>2</sub> into the aqueous phase, while the chemistry of the\npolymer can control the interfacial barrier for CO<sub>2</sub> permeation\nand the interfacial concentration of reactive AAs. The derived knowledge\nof the material properties achieved here can aid in the design of\nDAC systems with improved performance.