Materials with nanoscale dimensions offer several important benefits over bulk materials (e.g. increased surface area, low-cost, deviation from bulk properties, etc.). Such materials are critical components for next-generation energy storage materials, optoelectronic devices, and catalyst systems. However, these materials are often processed in liquid media, and their diminutive structures are fragile in the presence of capillary forces. As such, preparing uniform and stable nanomaterial coatings is a significant challenge. Herein, we discuss an approach where the substrate itself is factored into the assembly and growth of these materials. First, nanoporous surfaces were utilized to achieve a uniform deposition of one-dimensional (1D) and two-dimensional (2D) nanomaterials for high performance transparent conductive films. Suspensions of silver nanowires (AgNWs, 1D) and graphene oxide (GO, 2D) were deposited on superhydrophilic surfaces, which we generated through layer-by-layer assembly. It was discovered that coating defects (e.g., coffee-ring effect) were suppressed by the rapid wetting of suspensions into a thin liquid sheet on superhydrophilic surfaces. Uniform composite films were fabricated which exhibited a low sheet resistance and high percent transmittance, with minimal surface roughness. The growth of conformal Au coatings on the AgNW network stabilized the film against oxidation and granted mechanical stability through subsequent aqueous processing. Next, metal organic frameworks (MOFs) on with accessible open-metal sites were grown on electrospun hydrogel fibers (EHFs), with the fibers playing a role in their formation and stable surface bonding. Crystalline MOFs with tunable dimensions were grown on EHFs composed of crosslinked polyallylamine and polyacrylic acid. The physical properties of the fibers, such as polymer composition and the fiber diameter, had a direct role in the tuning of the MOF size and distribution on the EHFs. Last, the controlled growth of self-supported tungsten metal oxide nanosheets was investigated. Their potential as electrocatalysts and as high surface-area supports for other materials is discussed. Through salt-mediated growth, the macroscopic nanosheets of alkali (K+, Rb+, or Cs+) intercalated oxides could be produced uniformly on various tungsten metal surfaces. Anodization to adjust the surface texture altered the wettability and facilitated even salt deposition on these surfaces, resulting in a uniform nanosheet growth.
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Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Fox, David, "Surface Engineering for Controlled Growth and Deposition of Nanomaterials - Assembly and Design at the Nano-Microscale" (2022). Electronic Theses and Dissertations, 2020-. 1200.
Restricted to the UCF community until August 2022; it will then be open access.