Hierarchical MOF-Embedded PVDF Nanofibers: In Situ Growth Approach for Selective CO₂Adsorption and CH₄Purification

In response to the global drive toward a sustainable, low-carbon future, carbon dioxide (CO₂) capture and storage technologies have become essential tools for reducing greenhouse gas emissions. Metal–organic frameworks (MOFs), known for their exceptional porosity, tunable pore structures, and diverse chemical functionalities, offer strong potential for CO₂capture applications. Nonetheless, the inherent brittleness and limited processability of bulk MOF crystals pose significant challenges in fabricating flexible MOF-based nanofibrous membranes. Herein we introduce a robust and scalable strategy for producing self-standing and flexible PVDF@Cu₃(BTC)₂nanofiber membranes with uniform and stable MOF growth, achieved via a combination of electrospinning, in situ MOF crystallization, and thermal activation. The fabrication process involves embedding Cu²⁺ions into the PVDF matrix during electrospinning, followed by a rapid room-temperature crystallization step lasting just 15 s. The resulting PVDF@Cu₃(BTC)₂membranes exhibit excellent CO₂adsorption performance, reaching 4.6 mmol/g at 298 K and 100 kPa, along with a high CO₂/N₂selectivity of 28.42 and outstanding cycling stability. After 50 adsorption–desorption cycles, the membrane retains 94.12% of its initial capacity (4.33 mmol/g), highlighting its long-term durability and potential for practical deployment. Mechanical testing further revealed enhanced properties, with a tensile strength of 8.63 MPa (a 43% increase over pure PVDF), an elongation at break of 9.04%, and a storage modulus of 7.14 × 10³MPa confirmed by dynamic mechanical analysis (DMA). These improvements are attributed to strong interfacial bonding between the MOF and polymer phases resulting from the in situ growth process. Thus, this cost-effective and scalable approach enables the integration of MOFs into flexible nanofiber membranes, offering a promising route for efficient postcombustion CO₂capture technologies.