(354h) Exploring Sustainable Approaches to Fabrication of Robust MOF-Functionalized Hybrid Nanofibrous Aerogels

There is growing interest in sustainable strategies for developing multifunctional materials that avoid extensive use of organic solvents and complex reaction steps. Among the newly developed multifunctional materials, metal organic frameworks (MOFs), porous crystalline compounds classified as coordination polymers, stand out. Their three dimensional (3D) network structures, featuring extremely high surface areas and pore volumes, make them highly attractive for diverse applications including gas storage, separation, catalysis, sensing, drug delivery, and energy storage. However, MOFs are commonly synthesized as powders, which limits their practical applications. To overcome this, embedding MOFs into a stable host matrix is essential. Aerogels, with their ultra-lightweight characteristics, exceptional porosity, low density, and high specific surface area, are excellent candidates for this purpose.

In this study, we explore the use of MOF impregnated aerogels as a versatile material platform for various environmental remediation applications. Metal organic frameworks are known for their utility in separation processes, gas adsorption, catalysis, and energy storage, owing to their high surface area and porosity. However, their powdered form often suffers from limitations such as agglomeration and poor mechanical integrity. Integrating MOFs into aerogels addresses these challenges by providing a 3D macrostructure that improves handling and durability. We employ a versatile one-pot strategy to grow ZIF-8 MOFs on nanofibrous aerogels (NFAs) using vapor phase deposition and a solvent free approach. This facile and robust methodology results in the fabrication of a 3D self-supported cellular structure with elasticity, low density (approximately 10 mg/cm³), and hierarchical porosity consisting of primary (1 to 5 µm) and secondary pores (10 to 60 µm). Mechanical compressibility tests confirm the durability and resilience of the MOF NFAs, making them suitable for mechanically stressful environments. The developed aerogels demonstrate high CO₂ adsorption capacity (4.04 mmol/g), exhibiting excellent performance in CO₂ separation and selectivity. The incorporation of MOFs into the aerogel matrix maximizes the accessible surface area and exposes active sites within the micropores of ZIF-8, enhancing the interaction with CO₂ molecules. Furthermore, the aerogel shows remarkable efficiency in removing heavy metals, particularly Cu(II) ions with over 99% removal. This performance is attributed to the thin and uniform ZIF-8 coating on the NFA, which allows better exposure of active sites for pollutant binding. We compare different strategies for introducing the metal oxide precursor, including atomic layer deposition (ALD), in situ incorporation into the nanofibers during electrospinning, and the growth of metal oxide nanorods on the NFAs. In all approaches, the resulting aerogels retain their low density, highly porous architecture, and excellent mechanical stability under strain (up to 80 percent), even after MOF integration. These hybrid NFAs hold strong potential in environmental and biomedical fields, including sorption, catalysis, filtration, and water purification, offering scalable, sustainable, and high performance materials for next generation applications.