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Design and controlled synthesis of complex metal oxide nanostructures and study of their advanced energy applications.

机译：复杂金属氧化物纳米结构的设计和控制合成及其先进能源应用研究。

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摘要

Nano-structured metal oxides are of significance for fundamental science and practical applications because of their widely tunable physiochemical properties and excellent stability under various conditions. The synthetic chemistry of metal oxide nanostructures with controlled properties and innovation of their device applications are two interesting and crucial topics towards large-scale industrial production and commercialization. The focus of this dissertation is on the design and controlled synthesis of wide-bandgap metal oxide semiconductor nanostructures and study of their device applications for electrocatalysis and photocatalysis. The controlled hydrothermal synthesis of p-type copper-based delafossite compounds (e.g. CuGaO2) and n-type titanium oxide (i.e., TiO2) on substrates are systematically studied. Their structural, chemical and optical properties are characterized via X-ray diffraction, electron microscopy, photoelectron spectroscopy and diffuse-reflectance spectroscopy. The obtained CuGaO2 and TiO 2 nanostructures have been applied as semiconductor electrodes in p-type dye-sensitized solar cells, lithium-air and lithium-iodine solar batteries. A combination of absorption spectroscopy, electro-analytical techniques and photoelectrochemical methods are employed to evaluate the materials electrochemical and electronic performance within different device configurations.;Obtaining delafossite CuGaO2 nanoparticles is challenging but desirable for high-surface area device applications such as dye-sensitization and trace gas detection. The phase formation and crystal growth mechanism of delafossite CuGaO2 under low-temperature hydrothermal conditions are studied. The stabilization of CuI cations in aqueous solution and the controlling of the hydrolysis of GaIII species are found to be the two crucial factors that determine the phase formation. The oriented attachment (OA) growth is proposed as the crystal growth mechanism to explain the formation of large CuGaO2 nanoplates. Delafossite CuGaO2 nanoparticles on a 20 nm-size have been successfully synthesized for the first time. The synthesized light-colored CuGaO2 is applied as photocathodes in p-type dye-sensitized solar cells for the first time and presents significantly higher photovoltage compared to conventional NiO-based solar cells. Under 1 Sun AM 1.5 illumination, a Voc of 357 mV has been achieved, which is among the highest values that have been reported for p-DSSCs.;Well-aligned TiO2 nanorods on stainless steel and titanium substrates and nano-particles are synthesized through the hydrothermal process under controlled acidic conditions. The dye-sensitized TiO2 nano-structures have been applied as photoelectrodes in solar-powered electrochemical energy storage devices (i.e., solar batteries), for the simultaneous conversion and storage of solar energy. The solar battery integrates a photo-electrochemical cell and an electrochemical cell into a single device and is able to harvest solar energy and store it in-situ within the device via a photocharging process and distribute the energy as electric power when needed. A lithium-oxygen (Li-O2) solar battery is demonstrated with a dye-sensitized TiO 2 photoelectrode. A triiodide/iodide redox shuttle is used to couple a built-in nano-structured photoelectrode with the oxygen air electrode for the photo-assisted charging of a Li-O2 battery. On charging under illumination, triiodide ions are generated on the photoelectrode, and subsequently oxidize Li2O2. Because of the contribution of the photovoltage, a "negative" charging overpotential appears. The introduction of the TiO2 photoelectrode here offers a novel strategy to address the overpotential issue of current non-aqueous Li-O2 batteries. Another lithium-iodine (Li-I) solar flow battery (SFB) has also been constructed with integrating the TiO2 semiconductor photoelectrode with a Li-I redox battery. During the photo-assisted charging process, I- ions are photoelectrochemically oxidized to I3-, harvesting solar energy and storing it as chemical energy. The Li-I SFB can be charged at a voltage of 2.90 V under 1 sun AM 1.5 illumination, which is lower than its discharging voltage of 3.30 V. The charging voltage reduction translates to energy savings of close to 20% compared to conventional Li-I batteries.
机译：纳米结构的金属氧化物因其广泛的可调节的理化性质和在各种条件下的出色稳定性而对基础科学和实际应用具有重要意义。具有受控性能的金属氧化物纳米结构的合成化学及其器件应用的创新是大规模工业生产和商业化的两个有趣且至关重要的主题。本文的研究重点是宽带隙金属氧化物半导体纳米结构的设计与控制合成及其在电催化和光催化领域的应用研究。系统研究了p型铜基铜铁矿化合物（例如CuGaO2）和n型二氧化钛（即TiO2）在基底上的受控水热合成。它们的结构，化学和光学性质通过X射线衍射，电子显微镜，光电子能谱和漫反射光谱来表征。所获得的CuGaO 2和TiO 2纳米结构已经被用作p型染料敏化太阳能电池，锂空气和锂碘太阳能电池中的半导体电极。结合吸收光谱法，电分析技术和光电化学方法来评估材料在不同器件配置下的电化学和电子性能。获得铜铁矿CuGaO2纳米颗粒具有挑战性，但对于高表面积器件应用（如染料敏化和热敏化）是理想的。微量气体检测。研究了铜铁矿CuGaO2在低温水热条件下的相形成和晶体生长机理。发现水溶液中CuI阳离子的稳定化和GaIII物质水解的控制是决定相形成的两个关键因素。提出了定向附着（OA）生长作为晶体生长机理，以解释大型CuGaO2纳米板的形成。首次成功合成了20 nm尺寸的Delafossite CuGaO2纳米颗粒。合成的浅色CuGaO2首次在p型染料敏化太阳能电池中用作光电阴极，并且与常规的NiO基太阳能电池相比，呈现出明显更高的光电压。在1 Sun AM 1.5照明下，已达到357 mV的Voc，这是p-DSSCs报道的最高值。在不锈钢和钛基底上排列良好的TiO2纳米棒和纳米颗粒通过合成在受控的酸性条件下进行水热过程。染料敏化的TiO 2纳米结构已被用作太阳能电化学能量存储装置（即，太阳能电池）中的光电极，用于同时转换和存储太阳能。太阳能电池将光电化学电池和电化学电池集成到单个设备中，并能够收集太阳能并通过光充电过程将其原位存储在设备中，并在需要时将其作为电能分配。锂氧（Li-O2）太阳能电池用染料敏化的TiO 2光电极进行了演示。三碘化物/碘化物氧化还原梭用于将内置的纳米结构光电极与氧空气电极耦合，以对Li-O2电池进行光辅助充电。在照明下充电时，三碘化物离子在光电极上产生，然后氧化Li2O2。由于光电压的作用，出现“负”充电超电势。此处引入TiO2光电极提供了一种新颖的策略，可以解决当前非水Li-O2电池的过电位问题。还已经构造了另一种锂-碘（Li-I）太阳能液流电池（SFB），其将TiO 2半导体光电极与Li-I氧化还原电池集成在一起。在光辅助充电过程中，离子被光电化学氧化为I3-，收集太阳能并将其作为化学能存储。 Li-I SFB可以在1个太阳AM 1.5光照下以2.90 V的电压充电，这比其3.30 V的放电电压要低。与传统的Li-I相比，充电电压的降低可节省近20％的能量我电池。

著录项

  • 作者

    Yu, Mingzhe.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Materials science.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 190 p.
  • 总页数 190
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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