Hierarchical Mesoporous Metal-Organic Frameworks for Enhanced CO2 Capture

Hierarchical porous materials are promising for catalyst, separation and sorption applications. A ligand-assisted etching process is developed for template-free synthesis of hierarchical mesoporous MOFs as single crystals and well-intergrown membranes at 40 degrees C. At 223K, the hierarchical porous structures significantly improve the CO2 capture capacity of HKUST-1 by more than 44% at pressures up to 20kPa and 13% at 100kPa. Even at 323K, the enhancement of CO2 uptake is above 25% at pressures up to 20kPa and 7% at 100kPa. The mesoporous structures not only enhance the CO2 uptake capacity but also improve the diffusion and mass transportation of CO2. Similarly, well-intergrown mesoporous HKUST-1 membranes are synthesized, which hold the potential for film-like porous devices. Mesoporous MOF-5 crystals are also obtained by a similar ligand-assisted etching process. This may provide a facile way to prepare hierarchical porous MOF single crystals and membranes for wide-ranging applications.