Abstract:
Hierarchically Porous Metal-Organic Frameworks: A Versatile Platform for Catalysis
Metal–organic frameworks (MOFs) are known for their high crystallinity and high porosity. The well-defined structure makes it possible to study MOF materials on an atomic scale. However, the well-defined structures of MOFs also limit the pore sizes and pore architecture. For example, most of the reported MOFs are microporous, with pore sizes ranging from 1.0 nm to 10.0 nm. The architectures of MOF pores are also limited to channels (square, hexagonal, trigonal, etc.) and cages (tetrahedral, octahedral, cubic, cuboctahedral, etc.). Though the combination of metal centers with organic ligands could potentially result in unlimited numbers of structures, the type of pores, pore sizes, and pore surfaces are very limited. It is vital to develop MOF materials that possess hierarchical pores. Hierarchically porous MOFs would contain assorted pore sizes, pore shapes, and pore surfaces, as the metal centers and the organic linkers are connected in a more random fashion.
We have developed a facile synthesis method to prepare hierarchically porous MOFs (HP-MOFs) with low crystallinity. These materials formed through the interconnection of MOF nanocrystals to form larger nanoparticles. The nanoparticles contain pores ranging from several angstroms to several nanometers. Such materials could be realized using very simple organic linkers such as terephthalic acid. HP-MOFs are excellent catalysts themselves as the low crystallinity guarantees the missing linker or missing metal defects, which generates catalytic active centers. HP-MOFs are also ideal candidates as support for preparing multifunctional catalysts. As there are missing linker sites, secondary metal centers could be incorporated into HP-MOFs through post-synthetic modifications. We have prepared HP-MOFs containing active centers through both linker incorporation and secondary metal incorporation. These HP-MOF-supported catalysts have been studied for several emerging reactions, such as epoxidation reactions, CO2 fixation reactions, and coupling reactions. The HP-MOF materials could also be modified using a mixed ligand approach to prepare materials with tunable acid and base sites, which in turn influenced the catalytic performance.
Speaker Biography:
Dr. Zhang obtained his BS degree in Chemistry from Jilin University China in 2008. He started his Ph.D. study in 2009 at the University of South Carolina in the Department of Chemistry and Biochemistry under the guidance of Prof. Richard Adams. He worked on the design, synthesis and application of transition metal carbonyl cluster complexes with a focus on platinum group metals. After obtaining his Ph.D. degree in 2013, he joined Prof. Hong-Cai Zhou’s group as a postdoc at Texas A&M University and started to work on Metal–Organic Frameworks (MOFs). His research was focused on the design and synthesis of luminescent MOFs and their applications in sensing. He started his independent career at Washington State University in 2016 in the Department of Chemistry. His current research focuses on the development of multifunctional porous materials for catalysis.
Thursday, February 23, 2023
9:30 a.m., Gant North (GN) 20
Livestream link: http://www.kaltura.com/tiny/lqwur
For more information, contact: Katie O'Keefe/Chemical & Biomolecular Engineering Department at (860) 486-4020/katie.okeefe@uconn.edu