(139a) Identifying Molecular Descriptors for CO2 Chemisorption in Eutectic Mixtures Using High-Throughput Screening

Designing new materials for the direct air capture (DAC) of atmospheric CO₂ is essential to limit global temperature rise below 1.5 ^oC by 2050, with these new negative emission technologies (NETs) required to remove an estimated 10 gigatonnes of CO₂ annually. These technologies necessitate discovering new materials that can reversibly bind CO₂ under diverse environmental conditions with minimal energy requirements. Eutectic mixtures are one such class of materials that exhibit excellent properties for DAC. Eutectic mixtures consist of hydrogen bond acceptors (e.g., halide salts) and hydrogen bond donors (e.g., alcohols, amines, or amides) that together form a complex, dynamic liquid structure. Prior research highlights how CO₂ uptake performance is tunable by changing the components of the eutectic mixtures, allowing for CO₂ uptake optimization. However, at present, the design rules governing uptake remain unknown for these materials, which inhibits rational materials development. Therefore, we utilize high-throughput screening to understand the structure-function relationship behind CO₂ chemisorption in different eutectic mixtures. Specifically, we use quantum chemical calculations to screen different combinations of hydrogen bond acceptors and hydrogen bond donors. We compute the CO₂ binding and hydrogen dissociation energies for each species in our libraries, and then construct thermodynamic pathways for CO₂ binding and proton transfer reactions (as both reactions are fundamental to DAC in eutectic mixtures). Ultimately, this work identifies key descriptors that are important for CO₂ chemisorption. Our findings have significant implications for experimental synthesis, characterization, and performance evaluation of new eutectic mixtures for DAC, leading to the rational design of new eutectic mixtures with optimal CO₂ absorption. Ultimately, filling essential gaps in eutectic mixtures performance for DAC makes them a more viable NET.