Size-Controllable Synthesis of ZIF-8 and Derived Nitrogen-Rich Porous Carbon for CO2 and VOCs Adsorption

It's acknowledged that surface chemical and pore structure of adsorbent are main parameters to determine adsorption results. Herein, we prepared zeolitic imidazolate frameworks-8 (ZIF-8) with different average sizes (50, 120, and 2200 nm) and demonstrated their specific surface area and pore volume decreased with increasing particle size. ZIF-8 (ZN) exhibits a large specific surface area (1626.4 m(2) g(-1)) and total pore volume (1.088 mL g(-1)), but it has been shown to lack the non-specific adsorption capacity for the adsorbate. Carbonization at 800 degrees C is proved to be an effective method to expose massive surface nitrogen-containing functional groups and adjust the aperture to an appropriate pore size range for derived porous carbon of ZIF-8 (ZCN). High nitrogen content (18.7 at. %) greatly improves the affinity for CO2 and Volatile Organic Compounds (VOCs), as explained by the density functional theory (DFT) calculation results. Meanwhile, particle size influences the pore-forming results after carbonization directly. Among them, ZC50 generates a certain amount of narrow micropore in range of 0.7-1.0 nm, located in the optimal pore size range of CO2 adsorption calculated by Grand canonical Monte Carlo (GCMC) simulation, thus possessing the largest CO2 adsorption capacity (4.03 mmol g(-1) at 25 degrees C). Besides, ZC120 exhibits more superior mesopore structure that could strengthen multilayer adsorption for VOCs.