Dual-functional LDH interface engineered stable SiO₂@LDH-based porous liquids for efficient CO₂ capture

Porous liquids (PLs), as novel materials combining liquid fluidity with permanent porosity, demonstrate significant potential in gas capture and separation. However, the core challenge lies in achieving long-term stable dispersion of porous guests within sterically hindered solvents while maintaining pore accessibility. This work proposes a dual-functional layered double hydroxide (LDH) interfacial engineering strategy, successfully constructing stable porous SiO₂@LDH-based PLs. Cross-grown LDH nanosheets act as a physical barrier, effectively preventing steric solvent molecules from entering SiO₂ pores, thereby preserving abundant nanoscale cavities within the PL for CO₂ capture. Meanwhile, the abundant hydroxyl groups on LDH nanosheets form hydrogen bonds with the sterically hindered solvents, significantly enhancing the dispersion stability of the pore generators and preventing aggregation and sedimentation. The resulting PL exhibits outstanding long-term stability (>6 months without sedimentation) and highly efficient CO₂ capacity (1.51 mmol/g at 10 bar and 25 °C). Furthermore, this PL exhibits excellent selectivity (with a selectivity of 170 when simulating flue gas with a CO₂: N₂ ratio of 15%/85%) and cycle stability (retaining 97% of its maximum CO₂ capacity after 10 cycles). Isothermal adsorption models and adsorption kinetics models confirmed that the process primarily involves heterogeneous multilayer physical adsorption, thereby avoiding the capacity loss and energy consumption associated with regeneration caused by chemical absorption in traditional CO₂ absorption liquids. This study presents a novel and versatile interface design method for fabricating high-performance, stable PLs for CO₂ capture.