Direct air capture (DAC) of CO2, offers a promising route to solve climate change, which is undoubtedly one of the greatest challenges of the 21st century. However, the low concentration of CO2 in the atmosphere makes DAC challenging. Current technologies utilize liquid sorbents such as hydroxides or alkanolamines to absorb CO2. Slow kinetics, loss of sorbent via evaporation, high regeneration temperatures, etc. hinder commercial viability of such technologies. Amine functionalized polymers have been previously demonstrated as a step in the right direction towards effective CO2 sorbent alternatives with lower regeneration energy requirements and fast kinetics. Guanidine with its high amine availability has become a molecule of interest in recent years for CO2 sorption. In this work, we explore high surface area guanidine based polymeric sorbents that serve as high performance materials with excellent kinetics, sorption capacity and fast and low energy regeneration. First, we examine the CO2 sorption potential of L-Arginine amino acid that has a guanidine group in the molecule. We show that the incorporation of L-Arginine onto high surface area poly(vinyl alcohol) (PVA) electrospun mats significantly improves sorption performance. Secondly, we demonstrate the potential of poly(vinyl guanidine) (PVG) as a potential DAC sorbent. Electrospinning the PVG into nanofibers helps the material to attain fast kinetics and high sorption capacity on exposure to lab air. To simulate real world conditions, all testing was performed using lab air, simulating average wind speed conditions, with no packing of the material in the testing chamber. Thus, we succesfully demonstrate passive CO2 sorption of these high surface area materials. The PVA-Arginine and PVG nanofibers show excellent passive CO2 sorption capacities (Figure 1) of upto 579 µmol g-1 and 703 µmol g-1 respectively over a period of 2 h while also displaying fast desorption kinetics.

High surface area guanidine based polymeric materials for direct air capture of CO2

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