Role of the third component in CO ₂ absorption by tetrabutylammonium bromide‐based deep eutectic solvents

Deep eutectic solvents (DESs) represent promising carbon dioxide (CO 2 ) absorbents. In this study, experimental and molecular simulation studies were conducted to investigate the effects of incorporating a third component on the CO 2 absorption capacity of DESs using 3‐aminopropanol and monoethanolamine as hydrogen bond donors (HBDs). Piperazine (PZ) was introduced as a secondary HBD, while water or methanol (H 2 O or MeOH) was incorporated into the DES as a cosolvent. The introduction of these third components significantly enhanced the CO 2 absorption performance; however, the high viscosity restricted further CO 2 uptake enhancement of the PZ‐functionalized DES. Fourier‐transform infrared analysis confirmed that CO 2 was chemically absorbed by all four DES systems. The two cosolvents effectively reduced the viscosity and significantly improved the CO 2 absorption performance of the DESs. Furthermore, molecular dynamics simulations demonstrated that the cosolvents do not alter the interaction patterns but enhance the effective contact between the DES components and CO 2 .