Nanomaterial synthesis and characterization for energy storage and conversion devices.

摘要

Synthesis conditions and characterization techniques were investigated for a variety of nanomaterials that have potential for use in a plethora of energy storage and conversion devices, such as photovoltaics, thermionic emitters, lithium-ion batteries, and PEM fuel cells. A portion of this work focused on the development of a chemical vapor deposition synthesis technique for multi-walled carbon nanotubes (MWNTs) using an iron dimer in xylene as a liquid catalyst precursor. The optimization of synthesis conditions for this technique was subsequently followed by the development of a quantitative purity assessment method for MWNTs from Raman spectroscopy, which involves the ratios of peak heights in Raman spectra. Initial work in the development of this purity assessment method was extended to a second Raman excitation energy, and a universal equation of purity was developed for two excitation laser energies. The capability exists to develop free-standing electrode papers from these synthesized MWNTs for several of the aforementioned applications. A large portion of this work also focused on the characterization of materials commonly used in organic solar cells with the technique of cyclic voltammetry. Electrochemical measurements of semi-conducting CdSe quantum dots, fullerene derivatives, and polymers (MEH-PPV, P3HT, and MDMO-PPV) were completed to determine the band gap, ionization potential, and electron affinity of these materials in order to improve device fabrication by offering the capability of pre-selecting the materials incorporated in a given composite. This reduces time, energy, and expenses involved with fabrication, along with furthering the understanding of interactions between materials in a composite at the electronic level. This work has offered important contributions to the field of alternative energy by making strides in synthesizing, characterizing, and selecting appropriate materials for use in energy storage and conversion devices.