ZIF-8 based materials for CO₂ capture: synthesis, functionalization, and adsorption performance

Zeolitic imidazolate framework-8 (ZIF-8) has emerged as an important candidate for next-generation carbon capture technologies due to its unique porosity, structural robustness, and tunability. This review critically examines the molecular and material design principles behind ZIF-8's performance in selective carbon dioxide (CO₂) adsorption under realistic conditions. We explore the intrinsic crystallographic features that enable size-selective molecular sieving and physisorption-dominated uptake, as well as strategies for chemical functionalization that enhance affinity through amine grafting and the exchange of polar linkers. Synthesis methodologies ranging from conventional solvothermal to innovative green and mechanochemical routes are analyzed for their impacts on structural integrity, scalability, and adsorption efficacy. Composite systems comprising polymers, ionic liquids, and carbonaceous materials are discussed, highlighting the advances in membrane integration to enhance permeability and selectivity. We also evaluate performance metrics, including capacity, selectivity, cyclic stability, and regeneration energy, and contextualize them against competing candidates and industrial benchmarks. Challenges such as moisture sensitivity, pore blockage, and sustainable manufacturing are critically addressed, alongside opportunities in defect engineering, stimuli-responsive adsorption, and system-level integration. By providing a holistic framework that combines molecular insights, synthetic innovation, and application-driven designs, this review positions ZIF-8 as a versatile platform for scalable, energy-efficient CO₂ capture solutions to global climate mitigation efforts.