Dual synergistic effect of the amine-functionalized MIL-101@cellulose sorbents for enhanced CO2 capture at ambient temperature

The development of high carbon dioxide (CO2) sorption capacity materials is necessary for the deployment of the CO2 capture and storage strategy. Metal-organic frameworks (MOFs) have emerged as promising substitutes for traditional liquid and solid CO2 capture sorbents due to their high surface area, tunable pore size, diverse composition, and various physical and chemical properties. However, MOFs feature the intrinsic limitations of powder agglomeration, weak binding affinity, and sluggish diffusion kinetics, thus hindering their industrial application in CO2 capture. Herein, we design an amine-functionalized MIL-101@cellulose (NH2-MIL-101@BM) composite sorbent by anchoring NH2-MIL-101 nanoparticles onto the BM matrix through hydrogen bonding interaction. The dual synergistic effect, origin from the physical sorption synergistic effect and chemisorption synergistic effect proposed between NH2-MIL-101 and BM, not only facilitates the mass transfer of CO2 by reducing the diffusion resistance through hierarchical-pore structure but also offers stronger sorption sites with CO2 by increasing the adsorption energy of metal-CO2 or amine-CO2, which are confirmed by series of characterizations and theory functional calculations. Benefiting from the above merits, the NH2-MIL-101@20 %BM sorbent delivers a superior initial CO2 sorption capacity of 13.4 mmol/g when the BM doping amount is 20 wt% at 25 °C, and also shows good recycle stability even after 15 runs with maintainable structure. This work displays the in-depth mechanism understanding for enhanced CO2 capture, providing value inspiration for future MOF-based composite sorbent construction for CO2 capture at ambient temperatures.