Browsing by Author "Lei, Jincheng"
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Item Computational Study of Nanomaterials: Properties, Syntheses, and Applications(2022-01-06) Lei, Jincheng; Yakobson, Boris I.Nanomaterials have emerged as an exciting class of materials and one of the most active subjects of research in materials science due to their unique physical and chemical properties with enhanced performance over the bulk counterparts. In this thesis, computational methods, such as density functional theory (DFT) calculations and molecular dynamics (MD) simulations, are employed to study the properties, syntheses and applications of several nanomaterials, including carbon nanotubes (CNTs), transition metal dichalcogenides, and MXenes. Firstly, DFT calculations have been used to predict the stable phase and superconductivity of monolayer Mo2C, a MXene material. Secondly, MD simulations integrated with DFT calculations have been performed to interrogate the synthesis mechanisms of MoS2 and CNTs in chemical vapor deposition growth. Lastly, DFT calculations combined with experimental measurements have been carried out to investigate electrochemical catalysis regarding oxygen and carbon dioxide reduction reactions.Item Nickel particle–enabled width-controlled growth of bilayer molybdenum disulfide nanoribbons(AAAS, 2021) Li, Xufan; Li, Baichang; Lei, Jincheng; Bets, Ksenia V.; Sang, Xiahan; Okogbue, Emmanuel; Liu, Yang; Unocic, Raymond R.; Yakobson, Boris I.; Hone, James; Harutyunyan, Avetik R.Transition metal dichalcogenides exhibit a variety of electronic behaviors depending on the number of layers and width. Therefore, developing facile methods for their controllable synthesis is of central importance. We found that nickel nanoparticles promote both heterogeneous nucleation of the first layer of molybdenum disulfide and simultaneously catalyzes homoepitaxial tip growth of a second layer via a vapor-liquid-solid (VLS) mechanism, resulting in bilayer nanoribbons with width controlled by the nanoparticle diameter. Simulations further confirm the VLS growth mechanism toward nanoribbons and its orders of magnitude higher growth speed compared to the conventional noncatalytic growth of flakes. Width-dependent Coulomb blockade oscillation observed in the transfer characteristics of the nanoribbons at temperatures up to 60 K evidences the value of this proposed synthesis strategy for future nanoelectronics.