Density Functional Theory Studies of Nanoporous Materials
College of Engineering
Materials Science and Engineering
Carbon capture and sequestration (CCS) technologies aim to reduce the ever-increasing carbon emissions entering the atmosphere from coal-burning power plants. The advances that have been made in the field of nanoporous solids make these type of materials excellent candidates for innovative solid-CCS technologies which can, in principle, sequester carbon with less energy compared to currently implemented liquid-CCS technologies. Metal-organic frameworks (MOFs) consist of metal ions bridged by organic linkers, held together by a coordinated covalent network, forming finely tuned nanopore arrays. The flexibility and control of the MOF pores give unique adsorption and desorption affinity towards selected gases. It is the fine control of the nanoporous materials which also gives rise to many possible MOF structures and configurations.
Two MOFs of interest, Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN)4] and Cu-1,3,5-benzenetricarboxylate, or Ni2(CN)4-bpene and Cu-BTC respectively, were investigated through density functional theory (DFT) calculations using the Vienna ab-initio simulation package (VASP). Scripts were devised to generate multiple configurations for the Ni2(CN)4-bpene structure with different orientations of the bpene molecules, as well as for positioning of CO2 molecules in the Cu-BTC pores. The DFT calculations used to solve the electronic structure for these configurations ran in parallel on a computer cluster. The van der Waals' interactions in Ni2(CN)4-bpene play an important role in determining the structure. A candidate structure is found for the as-yet unknown structure of empty Ni2(CN)4-bpene. In Cu-BTC, the rigidity of the Cu-BTC pores makes structural relaxation studies simpler. Hence, analyzing the interactions of CO2 guest molecule with the pores becomes readily accessible through a DFT approach.
Correa Hernandez, Andres and Cockayne, Eric J., "Density Functional Theory Studies of Nanoporous Materials" (2018). 2018 Undergraduate Research and Scholarship Conference. 43.