Zero-dimensional (0D), one-dimensional (1D) and two-dimensional (2D) nanostructures for sustainable energy production and biolabeling applications

Sustainable energy production is a key goal in the immediate future to stave off anthropogenic climate change. Hydrogen as a fuel source is very promising, in that it can be used in fuel cells with water as the combustion product. Unfortunately, hydrogen production is expensive, and relies on methane reforming, which produces CO2 as a byproduct and by electrolysis from nuclear power plants. Hydrogen production through water splitting using photoelectrochemical (PEC) cells is the most egalitarian form of hydrogen production. Light energy is directly harvested to perform both oxidative and reductive processes in aqueous solutions. In our work, three different deposition techniques were used to produce PEC cells: (1) colloidal solutions, (2) pulsed laser deposition and (3) electron beam deposition. WO3 nanodisks were produced by a colloidal technique with Triton X-100 and 10,000 g/mol polyethylene glycol (PEG). Pulsed laser deposition (PLD), oblique angle deposition (OAD) and glancing angle deposition (GLAD) were used to produce ZnO thin films, ZnO nanoplatelets and ZnO nanoparticles, respectively. TiO2 nanorod arrays were produced by electron beam OAD, and produced dense and aligned arrays. These multidimensional nanostructures were fully characterized, and fashioned into PEC cells for water splitting characterization.;Biolabeling, in vivo site directed surgery and immunoassays are all being advanced with the use of fluorescent nanoparticles. One class of nanoparticles are semiconducting nanoparticles whose properties are defined by quantum mechanical principles, and have been coined quantum dots (QDs). QDs are superior over organic fluorophores, because they have full absorption and photoluminescent tunability through the visible and infrared range. They are resistant to photobleaching, can be conjugated to biologically relevant molecules, and can have multiple samples excited by a single excitation source. We examined CdTe QDs and grew silica (SiO2) shells on them, bioconjugated them to prostate antibody P-53, and confirmed bioconjugation by agarose gel electrophoresis. The CdTe/SiO 2 QDs were also conjugated to polystyrene microbeads and visualized with fluorescence microscopy. The silica shell was found to be a robust platform that stabilizes photoluminescence, acts as an anchor for molecular decoration and prevents aggregation.;1D CdSe quantum rods (QRs) were also synthesized by an organometallic route wherein the molecule TOPO was oxidized. The oxidized form of TOPO was found to produce DOPA, OPA and MOPA. These molecules help drive anistropic growth that produces 1D nanostructures. Without these molecules in solution QDs would be produced. A full characterization was performed using optical spectroscopy, electron microscopy, mass spectroscopy and nuclear magnetic resonance spectroscopy. We verified the presence of DOPA, OPA and MOPA, but the mechanistic details of the TOPO oxidation are still under investigation. The 4 nm x 20 nm CdSe QRs are a novel material which can be used in photovoltaic and optoelectronic devices.