The recent decade has witnessed the booming development of metal-organic frameworks (MOFs). Unlike their conventional counterparts (e.g., silica, activated carbon, zeolite), MOFs have crystalline structures, uniform yet tunable pore size, and versatile chemical compositions suitable as adsorbent materials and membrane materials for storage and separation applications. In this talk, I will introduce our group’s recent studies on the application of flexible MOFs for gas storage and separation. We have synthesized a series of flexible and stable MIL-53(Al) type MOFs, whose breathing behavior under high pressure of CH₄ can be controlled by systematic installation of hydrogen bonding sites into the frameworks. Such a control has been fine-tuned to induce high deliverable capacity of CH₄ in MOFs by changing pressure, temperature, density, and even synthetic conditions. We have also fabricated ultrathin 2D MOF membranes using exfoliated MOF nanosheets. Because of the flexibility of the MOF nanosheets, those membranes exhibit responsive gas separation behaviors under the stimuli of temperature or pressure, paving the way for the rational design of smart membranes for H₂ purification and CO₂ capture.

       Dan Zhao obtained his PhD degree in Inorganic Chemistry under the supervision of Prof. Hong-Cai Joe Zhou at Texas A&M University in 2010. After finishing his postdoctoral training at Argonne National Laboratory, he joined the Department of Chemical & Biomolecular Engineering at National University of Singapore in July 2012 as an Assistant Professor, and was promoted to Associate Professor with tenure in July 2018. His research interests include advanced porous materials and membranes with the applications in clean energy and environmental sustainability.