Hierarchical MOF-Embedded PVDF Nanofibers: In Situ Growth Approach for Selective CO₂ Adsorption and CH₄ Purification

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 CO2 capture 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)2 nanofiber 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)2 membranes exhibit excellent CO2 adsorption performance, reaching 4.6 mmol/g at 298 K and 100 kPa, along with a high CO2/N2 selectivity 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 × 103 MPa 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 CO2 capture technologies.