Coordination Pore‐Space Engineering in Robust Cage‐Like Metal‐Organic Frameworks for Highly Efficient CO ₂ Capture from Flue Gas

Abstract Developing novel porous adsorbents for highly selective CO ₂ from wet‐hot flue gas represents one of the most promising technologies to mitigate the negative impact on the environment via suppressing CO ₂ emissions, albeit it remains highly challenging due to the difficulty of achieving the trade‐off among adsorption capacity, selectivity, adsorption enthalpy, and stability. Herein, a facile coordination pore‐space engineering (CPSE) strategy is demonstrated to optimize the pore nanospace of the prototypical cage‐like MOF, proto ‐MFOF‐1, by virtue of an isostructural contraction protocol, for highly efficient CO ₂ capture from wet‐hot flue gas. Significantly, FJUT‐1, with excellent physiochemical stability, presents significantly improved CO ₂ capture capacity and CO ₂ /N ₂ selectivity compared with proto ‐MFOF‐1, due to the contracted cage window size, preserved cage volume, and functionalized cage surface decorated with fluoride/sulfate (F ⁻ /SO ₄ ²⁻ ) anions, and pyridine/benzene rings. Additionally, the practical separation performance for FJUT‐1 is examined by transient breakthrough experiments at 298–343 K, demonstrating impressive CO ₂ capture capacities of 2.29–0.80 mmol g ⁻¹ , which can be reserved under high humidity. The distinct adsorption mechanism has been well disentangled by in situ SCXRD, in situ FTIR spectrum, and molecular modeling, in which the strong electrostatic O···C═O, multiple C‐H···O hydrogen bonds, and guest‐guest interactions, collaboratively result in the highly selective CO ₂ capture performance.