Subcategory: Chemistry (not Biochemistry)
Christopher Copeland - Jackson State University
Methane gas is the predominant component of natural gas that has associated with it several health threatening effects such as asphyxiation due to oxygen displacement. It is a colorless, odorless, and extremely flammable gas that is very dangerous in confined spaces; so, there exists a need for materials with higher sensitivities and specificity for methane gas detection.
This investigation employs quantum chemical techniques to investigate a promising, relatively new, nanomaterial, boron-nitride nanotubes (BNNTs), for potential application in methane detection. The choice of Sc metal derives from the fact that BNNTs doped with Sc are the most stable of all 3d transition metals. A zigzag, (5,0), single-walled BNNT consisting of 72 atoms in total was chosen as the absorbent. The size of the systems under investigation constitutes the use of density functional theory (DFT) to accurately describe the electronic structure and energetics. All structures were fully optimized without symmetry constraints employing the cc-pVDZ basis set. The computed binding energies for preliminary and subsequent computations include corrections for zero-point energy, thermal contributions, and basis set superposition error. All computations have been performed using the Gaussian 09 Rev. D computational software and related graphics produced with the Gaussview 5 software.
Theoretical predictions at the B3LYP level indicate that substitutions of a B atom in the nanotube are more favorable than that of replacing a N atom. Band gap analysis, taken here as the energy difference of the high occupied and lowest unoccupied molecular orbitals, show a transition from insulating to semiconducting properties when doped with Sc. Binding energies of one methane adsorbed to the Sc atom in the doped nanotube show favorable adsorption characteristics (~6 eV), but a reduction in binding energy per methane molecule is observed as the number of methanes increase (~2.5 eV/Me for 3 methanes).
At the current stage of this work, it can be concluded that BNNTs are promising candidates for methane detection and storage given the favorable electronic properties. Because the electronic properties of the BNNTs are independent of chirality and tube length, further studies will be conducted to determine how adsorption characteristics and electronic properties are affected when tube diameter varies and when periodic boundary conditions are imposed.Not Submitted
Funder Acknowledgement(s): This research is supported by the NSF-CREST and Title III grant with special thanks to the Interdisciplinary Center for Nanotoxicity at Jackson State University.
Faculty Advisor: Jerzy Leszczynski, email@example.com