Simple and sustainable mechanosynthesis of a CALF-20@Fe3O4 composite for gas mixture separation

The development of sustainable sorbents for energy-efficient CO2 capture is a pressing challenge. Here we report a simple, solvent-minimized liquid-assisted grinding (LAG) route for the preparation of CALF-20 and its magnetic composite CALF-20@Fe3O4. The MOF synthesized in only 2 h exhibits high crystallinity, a BET surface area of ~600 m2 g−1, and a CO2 uptake of 5.0 mmol g−1 at 273 K and 1 bar, comparable to solvothermal benchmarks. Incorporation of 8 wt% Fe3O4 nanoparticles yields a composite with preserved porosity, strong CO2/N2 selectivity (S ≈ 323 at 273 K), and near-bulk magnetic properties. When shaped into poloxamer-bound granules, the composite retains its structural integrity while exhibiting an increased working capacity (1.4 mmol g−1) due to enhanced regenerability at 403 K. Under alternating magnetic fields, the granules achieve rapid, volumetric heating with specific absorption rates up to 80 W g−1, enabling fast sorbent regeneration. These results demonstrate that CALF-20@Fe3O4 unites the chemical robustness of CALF-20 with magnetic induction heating functionality, offering a scalable platform for low-energy post-combustion CO2 capture.