Immobilized ionic liquids/deep eutectic solvents in carbon capture: current progress and future potential

Global warming and the urgent need for net-zero emissions have intensified the search for efficient CO2 capture technologies. While the amine-based absorption technology has been widely used for CO2 capture, it faces high energy requirements for regeneration and degradation over time. Ionic liquids (ILs) and deep eutectic solvents (DESs) have emerged as promising alternatives due to their tunable properties and stability, but they also face challenges such as high viscosity and cost. One strategy to address these limitations is immobilizing ILs/DESs on a large surface, which not only reduces the required solvent volume but also enhances mass transfer rates. A variety of porous materials have been utilized for this purpose, including metal-organic frameworks, zeolitic imidazolate frameworks, zeolites, silica-based and carbon-based particles, polymeric particles, Al2O3, etc. However, there is a noticeable gap in comprehensive reviews on consolidating the reported data and analyzing the influence of key parameters, such as surface chemistry, pore size, pore volume, and surface area, on the CO2 capture performance. In this review, a detailed overview of all reported immobilized ILs/DESs composites for CO2 capture is provided, where the data are compiled and analyzed to offer an up-to-date resource for future research. The effects of structural properties and surface chemistry on the CO2 uptake are explored, with an investigation into whether a universal trend exists for enhancing the performance of the ILs/DESs-based composites.