Nanostructured materials have brought an unprecedented opportunity for advancement in many fields of human endeavor and in applications. Nanostructures are a new research field which may revolutionize people's everyday life. In the Thesis, I have usedtheoretical methods including density functional theory (DFT), molecular dynamic simulations (MD) and tight-binding methods to explore the structural, mechanical and electronic properties of various nanomaterials. In all this, I also paid attention topotential applications of these findings.First, I will briefly introduce the scientific background of this Thesis, including the motivation for the study of a boron enriched aluminum surface, novel carbon foam structures and my research interest in 2D electronics. Then I will review the computational techniques I used in the study, mostly DFT methods.In Chapter 3, I introduce an effective way to enhance surface hardness of aluminum by boron nanoparticle implantation. Using boron dimers to represent the nanoparticles, the process of boron implantation is modeled in a molecular dynamics simulation ofbombarding the aluminum surface by energetic B2 molecules. Possible metastable structures of boron-coated aluminum surface are identified. Within these structures, I find that boron atoms prefer to stay in the subsurface region of aluminum. By modeling the Rockwell indentation process, boron enriched aluminum surface is found to be harder than the pristine aluminum surface by at least 15%.In Chapter 4, I discuss novel carbon structures, including 3D carbon foam and related 2D slab structures. Carbon foam contains both sp2 and sp3 hybridized carbon atoms. It forms a 3D honeycomb lattice with a comparable stability to fullerenes, suggesting possible existence of such carbon foam structures. Although the bulk 3D foam structure is semiconducting, an sp2 terminated carbon surface could maintain a conducting channel even when passivated by hydrogen. To promote the experimental realization of this novel foam structure, I also propose a growth model. I postulate that preferred growth should occur near the grain boundary of a carbon saturated polycrystal of transition metal. These findings are supported by a calculation of carbon diffusion in the solid.2D semiconductors of group V elements are discussed in Chapters 5, 6, 7, and 8, including different phosphorus and arsenic structural phases. Structural and electronicproperties of bulk and few-layer black phosphorus, so-called phosphorene, are studiedin Chapter 5. In Chapter 6, I propose a new 2D structural phase of phosphorus,with the name blue phosphorus related to its wide predicted fundamental band gap. Then I move down in the periodic table and investigate the properties of grey arsenic in Chapter 7. Finally, I propose a tiling model to identify and categorize these structural phases in Chapter 8.
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