The chemistry of CO2 capture: amine, carbonate and ionic-liquid systems, and the emergence of reactive sorbents for downstream conversion.

Carbon dioxide capture is central to any credible strategy for reducing anthropogenic emissions, and the chemistry behind it spans a wide range of materials and mechanisms. This feature article provides a critical review of the main classes of chemical systems used for CO2 capture, including aqueous and supported amines, carbonate-based sorbents, high-temperature calcium looping materials, ionic liquids, and crystalline porous solids. These systems are considered within a common framework that balances binding strength, selectivity, working capacity, and regeneration energy. Particular focus is given to zeolites, whose well-defined microporous structures, tunable extra-framework cations, and established industrial use make them versatile candidates for selective CO2 physisorption. We highlight recent progress in cation engineering, hydrophobicity control, and shaped-body diffusion, including contributions from our own work and related studies from other groups. The article also discusses the rapidly growing field of reactive, or dual-functional sorbents, where CO2 capture is coupled directly with downstream conversion, narrowing the gap between capture and utilisation. Across these material families, a recurring design challenge emerges: increasing affinity and selectivity often raises the energy required for regeneration. We conclude by outlining the materials design principles and process-level considerations most likely to guide future advances in efficient and selective CO2 capture.