Recent developments and prospects of task-specific ionic liquids (TSILs) for scalable decarbonization toward negative emission technologies

Global warming, mainly driven by the emission of greenhouse gases such as carbon dioxide (CO2), remains one of the most urgent environmental challenges. Although amine-based solvents, particularly monoethanolamine (MEA), have long been used as conventional absorbents for CO2 capture and sequestration (CCS), their broader industrial deployment has been limited by high regeneration energy, corrosiveness, volatility, and long-term degradation. In this context, ionic liquids (ILs) have attracted growing interest as tunable CO2 capture systems due to their negligible vapor pressure, low volatility, non-flammability, structural flexibility, and adjustable CO2 affinity. This review critically examines recent progress in task-specific ionic liquids (TSILs) for CO2 capture, focusing on amine-functionalized ILs (AFILs), amino acid-functionalized ILs (AAILs), and amine-blended ILs (ABILs). Their performance is evaluated using normalized multi-criteria scoring based on CO2 uptake capacity, viscosity-related processability, operating conditions, and regeneration-energy considerations. The review also discusses pilot-scale progress, impurity tolerance, degradation pathways, and environmental safety. The performance analysis shows that while AFILs and AAILs can provide strong CO2 affinity, their scalability is often limited by viscosity and regeneration penalties. ABILs and hybrid IL-enhanced systems appear as more practical near-term options because their composition can be tuned to balance CO2 capacity, viscosity, stability, and energy demand. This review highlights the need to design TSILs not only for high CO2 absorption but also for durable, regenerable, and industrially processable carbon-capture performance.