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201899 https://hdl.handle.net/2286/R.2.N.201899 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2025 221 pages Doctoral Dissertation Academic theses en Gupta, Adway Singh, Arunima K Tongay, Seth A Botana, Antia S Zhuang, Houlong L Arizona State University Partial requirement for: Ph.D., Arizona State University, 2025 Field of study: Physics Lower-dimensional nanostructures, such as 2D nanosheets and quasi-1D nanoscrolls, are emerging as key materials in the global transition toward renewable energy. Their unique morphologies make them especially attractive for applications in solar-driven hydrogen production and hydrogen storage. However, most experimentally realized materials in this class originate from van der Waals (vdW) bonded bulk structures, constraining the range of usable compounds. Motivated by the urgent need to expand the materials landscape beyond vdW systems, the work in this thesis was focused on a comprehensive in silico investigation of non-vdW lower-dimensional nanostructures using advanced ab initio methods in condensed matter physics.First, 2D B4C nanosheets were studied, a material whose bulk counterpart lacks vdW bonding. Density functional theory (DFT) calculations revealed an anomalous stability for the nanosheets that resulted from the formation of covalent cage-like structures on their surfaces. These unique surface reconstructions also lead to novel electronic behavior like semiconductor-to-metal transitions and enhanced Seebeck coefficients—positioning non-vdW 2D nanosheets as both synthesizable and functionally promising. Inspired by a recent experimental method, a robust computational screening strategy was developed to identify suitable precursor materials for nanoscroll formation. A physio-mechanical model was constructed with input parameters derived from density functional theory (DFT), allowing for the prediction of equilibrium nanoscroll geometries and revealing a phase space of stability. Further exploration on strain-anisotropy–driven scrolling in Janus TMDC nanoscrolls was undertaken by identifying preferred scrolling directions and uncovering the role of intercalated solvents at the substrate interface. Ab initio molecular dynamics (aiMD) simulations shed light on the kinetics and driving forces of this transformation. Finally, the potential of these nanoscrolls for solar-driven hydrogen production and storage was assessed. Using many-body perturbation theory (GW+BSE), it was shown that their electronic and optical properties are highly tunable with interlayer spacing. AIMD simulations also revealed promising hydrogen storage capabilities, even in the presence of defects. Together, by uncovering the stability mechanisms and functional potential of lower-dimensional non-vdW nanostructures, this work not only challenges existing material constraints but also opens new pathways for their rational design, tailored for a sustainable energy future. Materials Science Physics Condensed Matter Physics 2D materials ab-initio Density Functional Theory Hydrogen Production Photocatalysis Quasi-1D Nanoscrolls Atomistic Modeling of 2D Nanosheets and Nanoscrolls of Non-van der Waals Layered Materials