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This dissertation, Electrochemical fabrication of metal/metal hydroxides nanostructured materials and its applications by Ya Huei, Chang, 張雅慧, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Electrochemical Fabrication of Metal/Metal Hydroxides Nanostructured Materials and Its Applications Submitted by Ya-Huei Chang for the degree of Doctor of Philosophy at The University of Hong Kong in August 2015 In order to survive in the harsh environments, natural creatures evolve unique wettability properties, for example, peanut leaf exhibits extreme water-repellency with high adhesive force, and Namib Desert beetle displays high wetting contrast patterns. Inspired by these natural creatures, a multifunctional surface which owns tunable wettability and switchable wettability between superhydrophilic (150) is developed. 3D nanosponge-like nickel oxyhydroxide/hydroxide (NiOOH/Ni(OH) ) films on FTO are fabricated through anodic plating. The as-prepared hydrophilic/superhydrophilic film can be further treated with non-fluorinated octadecyltrimethoxysilane (ODS) self-assembled monolayers (SAMs) or external stimuli of environmental chamber (EC) and UV/ozone. The post-chemical modification of ODS-SAMs on NiOOH/Ni(OH) films leads to an irreversible transition from superhydrophilic to superhydrophobic. Moreover, the optical transparency of NiOOH/Ni(OH) film at superhydrophobic state is kept with high adhesive force (53 μN). Instead, triggered with EC and UV/ozone alternatively, NiOOH/Ni(OH) films exhibit reversible and rapid switch between superhydrophobic and superhydrophilic over than ten cycles owing to the combined effects of chemical composition change and short-range ordered- disordered transition. The effectiveness of these achieved functions is demonstrated on the transparent or rewritable two-dimensional (2D) microfluidic channels. By virtue of switchable wettability and high compatibility with different metal electrolytes, the repertoire of NiOOH/Ni(OH) film is further extended to as an ideal hard template to fabricate metal nanoparticles (i.e., Au, Ni and Ag). Both the interior cavity of the mesorpores and top surface of the scaffolds of NiOOH/Ni(OH) film can serve as nucleation sites for electroplating depending upon the surface wettability. Therefore, shape-controllable (from nanoscale to sub- II microscale) and shape-variable metal nanoparticles are achieved. The rich nanostructures include peapod-like, spherical and dendritic nanocomposites with different optical responses. Furthermore, the metal nanoparticles could be easily isolated from the template in a nondestructive way. Finally, I accidentally discover that immersing the bulk metal thin film (i.e., Ag and Cu) into the NiOOH/Ni(OH) electrolyte could create flower-like Ag, Cu and Ag@Cu nanocrystals (NCs) during cyclic sweeping potential (CSP) on FTO 2+ with a pretreatment of bridge-linker. The roles of nickel ions (Ni ) are identified as the source of oxidative etchants and acetate ions (CH COO ) can help control the aspect-ratio and proportion of (111) to (100) facets. The local oxidative etching reaction induces the formation of the defective petal-like nanosheets which are self- assembled into the micrometer-sized flower-like NCs. Furthermore, it is demonstrated as a good candidate for sensing glucose mainly due to the existence of plenty of atomic steps. The detection limit of flower-like Ag NCs is as low as 0.1 4 -1 -2 nM with a superb s

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