奈米結構之過渡金屬氧化物和二硫氧化物為能源相關之應用

Nanostructured Transition Metal Oxides and Dichalcogenides for Energy-related Applications

伊伯漢(Mohammed Aziz Ibrahem)

指導教授 ： 朱治偉

共同指導教授 ： 張嘉升(Chia-Seng Chang)

國立臺灣大學/理學院/物理研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.00355

摘要

無資料

關鍵字

纳米 ； 金属氧化物 ； 金属二硫属化物 ； 能源 ； 有机太阳能电池 ； 锂离子电池 ； 日合成太阳能电池

並列摘要

In this thesis the applicability of the efficient production of low-dimensional materials under the effect of mechanical forces is assessed. The development of efficient synthesis methods capable of mass production of nanomaterials is becoming crucial. Two key technological transition metal materials, oxides and dichalcogenides are chosen as model systems. Among TMO, ZnO and MoO3 are chosen, while MoS2, WS2, and NbSe2 are chosen for TMDs. Braking-down of bulk ZnO found to increase the compatibility between ZnO nanoparticles and organic solvents increasing the repulsive forces among particles, preventing the ZnO nanoparticle from aggregation. The effect is attributed and related to the changes in the surface area. When the ZnO interlayer was present in the OSC, the vertical phase separation of the active layers prepared with and without solvent annealing exhibited similar gradient concentrations and, therefore, similar photocurrent generation. The bond breaking in MoO3 along the [001] direction consumes less energy because only one MoO bond connects the corner-shared octahedral, while the two MoO bonds connected along the [100] direction require more energy to break. Therefore, by applying mechanical force with various imposing times (15–90 min) Bulk MoO3 can directly converted to nanorods with average lengths of 0.5–1.5 μm and widths of approximately 100–200 nm. Relative to α-MoO3 microparticles, these nanorods displayed significantly enhanced lithium-ion storage properties with higher reversible capacities and better rate performance, presumably because their much shorter diffusion lengths and higher specific surface areas allowed more-efficient insertion/deinsertion of lithium ions during the charge/discharge process. Thermodynamically, the free energy of mixing for non-electrolytic systems predominate the solvent and solute mixing process. According to Hildebrand–Scatchard equation, the energy per unit area required to overcome the van der Waals forces is minimized when the surface energies of the nanosheets and solvent are matched. Although the strong attraction between the solvent and nanosheets is not sufficient to exfoliate sheets from the bulk materials, it still weakens the van der Waals interactions between adjacent layers. Therefore, it is required to incorporate an additional force to facilitate the exfoliation and isolation of individual nanosheets. Here, in bead-milling, this required force can be provided through the friction and sheer force of the beads on the layered materials. By utilizing these layered transition metal disulphide films as an electron extraction layer in inverted structure organic solar cell can deliver promising power conversion efficiency with high stability. Simple and facile methods for the large-scale syntheses of well-defined NbSe2 nanostructures in high yield have yet to be realized and that will have a great impact in a wide range of applications. One-step process for the preparation of NbSe2 nanosheets, nanorods and nanoparticles from pristine materials under the effects of shear and friction forces was demonstrated. DSSCs with NbSe2 nanosheets counter electrode (CE) achieved a conversion efficiency of 7.73%, superior to an efficiency of 7.01% for Pt-based CE. NbSe2 nanostructure provides a cost-effective CE alternative to the noble metal Pt in DSSCs.

並列關鍵字

Nanostructured ； Metal oxides ； Metal dichalcogenides ； Energy ； Organic Solar Cells ； Lithium Ion Battery ； Day Synthesis Solar Cells

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