Effective ethylene capture by hydrophobically engineered core-shell Cu-BTC@ZIF-8 for postharvest preservation

Core-shell Cu-BTC@ZIF-8 enhanced hydrophobicity without sacrificing ethylene adsorption. • ZIF-8 shell provided water blocking while enabling ethylene transport. • HMDS/PDMS integration improved water resistance, filler dispersion and membrane processability. • Active packaging membrane with ethylene-scavenging, antibacterial activity, and improved water stability. Ethylene accelerates postharvest ripening and quality loss of fruits and vegetables even at ppm levels. Copper-based MOFs, such as Cu-BTC, can capture olefins via open metal sites (OMS) through π-complexation, yet water sensitivity and powder form limit their use in humid, air-based transport. Here, we report an ethylene-scavenging composite membrane developed through a processable material-design strategy involving structural protection, surface engineering, and membrane integration. A ZIF-8 shell is grown in situ on Cu-BTC to form a microporous protective interface that suppresses water ingress and mitigates water-induced OMS deactivation, while its known aperture flexibility associated with 2-methylimidazolate linker motion is incorporated into the design to maintain ethylene transport through the shell under humid air. In air at 25 ± 2 °C and 50 ± 5% RH, Cu-BTC@ZIF-8 exhibited an ethylene uptake of 35.97 cm 3 (STP) g −1 over 72 h, exceeding pristine Cu-BTC. An ultrathin HMDS-derived siloxane layer was subsequently introduced, and the particles were embedded in PDMS to further improve water resistance and convert the powder adsorbent into a processable membrane form with improved engineering applicability. In an 80 L sealed chamber under real air, the Cu-BTC@ZIF-8 + HMDS|PDMS membrane showed an ethylene removal capacity of 34.71 cm 3 (STP) g −1 over 72 h based on MOF mass and retained approximately 80% of its initial performance after ten 72 h cycles. In a 10-day banana storage experiment at 25 ± 2 °C, the composite membrane delayed visible browning by 3–4 days compared with blank and pure PDMS controls and showed inhibitory activity against E. coli and S. aureus . This work proposes a feasible material-oriented strategy to enhance the water resistance and processability of Cu-BTC-based MOF materials, while avoiding compromising ethylene adsorption performance under real-air conditions.