Multifunctional and Hierarchical Porous ZIF‐8: Amine and Thiol Tagged via Mixed Multivariate Ligand Strategies for Enhanced CO₂ and Iodine Adsorption

Abstract

This study demonstrated a simple and innovative way of using the direct de novo synthesis to fabricate the mesoporous structure and diverse functionality of ZIF‐8 for environmental cleanup and gas storage applications. By introducing different ligands, we have developed a version of ZIF‐8 that could better capture carbon dioxide (CO2) and iodine. The ZIF‐8 was successfully designed to have the hierarchical and mesoporous structure with the functional groups of amine and thiol groups by adjusting the pKa values (from 8 to 12) of ligand instead of original ligand, 2‐methyl imidazole (Hmim, pKa~14.2). The modulation of ZIF‐8 particle size, porosity, and functional characteristics was achieved through varied ligands and their concentrations, streamlined into a single and room‐temperature synthesis condition. The resulting ZIF‐8 materials exhibit intricate hierarchical architectures and a high density of functional groups, significantly enhancing molecular diffusion and accessibility. Among the developed materials, ZIF‐8‐AS, featuring both amine and thiol groups, demonstrates the fastest adsorption kinetics and a twofold increase in iodine adsorption capacity (qm = 1101.5 mg·g−1) compared to ZIF‐8 (qm = 514.3 mg·g−1). Furthermore, the hierarchical mesoporosity of ZIF‐8‐A‐10.1 improves CO2 adsorption to 1.0 mmol·g−1 at 298 K, which is 1.3 times higher than that of the microporous ZIF‐8.