Counterion Effects on Moisture Swing Direct Air Capture Applications

Direct air capture (DAC) is essential for achieving reversing the growth in greenhouse gas emission. Conventional sorbent materials require a regeneration approach which is energy intensive. Here, we evaluate a novel moisture-swing direct air capture approach which utilizes water vapor as a means to regenerate a absorbent materials. We specifically examine five anions (carbonate, phosphate, sulfide, acetate, and borate) and study how they interact impact co2 absorption capacity and kinetics. We discovered that the local short-range order in micropores determines the amount of hydroxide formation in the moisture-controlled reversible hydrolysis/neutralization reaction to affect CO2 capture capacity. Among five anions, carbonate, phosphate, and borate exhibited greater ability to generate hydroxide and thus have higher capture capacity. A thorough understanding of the role anions impact moisture-swing DAC application can enable materials design strategies for advance climate materials.