From Pre to Post Reaction Conditions: The Transitioning Amino Acid Behavior at Air/Aqueous Interface under Direct Air Capture Conditions

To achieve global climate objectives, such as limiting the global temperature rise to less than 2C, the implementation of advanced negative emission technologies (NETs) is required. Among these, Direct Air Capture (DAC) using amino acids stands out due to lower volatility, nontoxicity, biodegradability, and scalability. Nonetheless, the optimization of DAC efficiency requires a comprehensive understanding of the CO₂ interaction mechanisms with amino acids at the air/aqueous interface. This study utilizes molecular dynamics simulations and Sum Frequency Generation (SFG) spectroscopy to characterize the interfacial behavior of three amino acids namely Valine, Leucine, and Phenylalanine, in both before and after CO₂ capture conditions. The study explores the outcomes of ion-generated competitive interactions on interfacial adsorption, orientation, and speciation, aiming to elucidate the fundamental processes that govern the direct air capture mechanism. Through this, we hope to inform the development of more effective interfacial systems for DAC, contributing to the reduction of atmospheric CO₂ and the mitigation of climate change.