Computational Study of Hydrogen Uptake in Metal Organic Framework Ni3(pzdc)2(ade)2 and Collecting Geometric Properties of Metal Organic Frameworks to Use as Descriptors in a Computational Database

Abstract

Metal organic frameworks (MOFs) are a class of nanoporous materials made of organic and inorganic structural building units (SBUs). MOFs have gathered interest for many applications due to their high tunability leading to materials with very diverse pore chemistries and geometries. The focus of this thesis is on studying the gas separation and storage capabilities of MOFs and analysing their geometric properties. The first part of this thesis work is a computational study of H2 uptake in the MOF Ni3(pzdc)2(ade)2 to understand its strong uptake. Synthesized in the lab of Professor Kyriakos Stylianou at the University of Oregon, the unactivated crystal structure of the MOF was experimentally determined and following the activation the MOF was found to have high uptake for H2 at low pressures. To understand the adsorption of H2 in the MOF, density functional theory (DFT) calculations were performed to explore the activated structure and understand the H2 binding in the material. The H2 uptake capacity was then explored computationally with grand canonical Monte Carlo (GCMC) simulations whereby the metal was changed to analyze the effects of the metal centre on hydrogen uptake. The second part of this thesis involved the calculation of geometric properties for the ARC-MOF database curated with the Woo lab that contains around 280K MOFs – both experimentally characterized and computer-generated structures. The database was created to provide the community with a diverse database of MOFs for which DFT derived partial atomic charges are available to conveniently perform high-throughput screening and data-driven studies. For this thesis, the relevant geometric properties for all MOFs in the database were calculated such as the accessible surface area, accessible volume, pore limiting diameter, and largest cavity diameter. The distribution of the descriptors was plotted and compared to existing databases to demonstrate the diversity of the database.