Ultra-small defect-engineered UiO-66 on cellulose nanocrystal template for advanced carbon dioxide capture membrane

Global warming and associated climate change, primarily driven by greenhouse gas emissions, are no longer a forecast but are now undeniable realities. Although membrane technology presents a highly cost-effective approach for carbon dioxide (CO2) capture, further research is required to overcome the inherent trade-off between selectivity and permeability to achieve enhanced performance. A novel defect-engineered ultrasmall cellulose nanocrystal (CNC)-templated UiO-66 MOF (CNC-UiO-66 hybrid) was synthesized to improve the performance of Pebax membranes. The elongated geometry of the CNC-UiO-66 hybrid creates extended facilitated transport channels for CO2, while the highly defective structure, induced by the presence of CNC during synthesis, enhances coordination interactions with both CO2 and the polymer matrix. As a result, Pebax incorporated with CNC-UiO-66 demonstrated increased crystallinity and thermal stability. The incorporation of as little as 1 wt % of the CNC-UiO-66 hybrid into Pebax membranes achieved a remarkable CO2 permeability of 1442 Barrer and a selectivity of 40, surpassing the Robeson upper bound (2008) for CO2/N2 separation. Cost analysis suggested that this membrane could reduce carbon capture costs to 62 USD per tonne, 10 USD less than conventional membranes. These results highlight the potential of CNC-UiO-66 hybrid membranes for efficient and costeffective CCUS applications, particularly in flue gas treatment.