Gradient Mesoporosity in Hierarchical ZIF-8 by Temperature-Modulated Soft-Templating

Abstract

Engineering hierarchical porosity in metal–organic frameworks (MOFs) is critical for improving mass transport and expanding their utility in catalysis, separation, and adsorption. We report a temperature-controlled soft-templating method for precise tuning of mesopore size in zeolitic imidazolate framework-8 (ZIF-8), employing a single amphiphilic block copolymer as the structure-directing agent. Systematic variation of the synthesis temperature yields a distinctive gradient mesoporous architecture, characterized by a progressive increase in mesopore diameter from the particle interior to the exterior. This strategy enables continuous control over mesostructure without the need for additional swelling agents or template exchange. The resulting trimodal porous ZIF-8 exhibits significantly enhanced structural accessibility and diffusion characteristics, providing a versatile platform for future studies in catalysis and molecular adsorption.