Synthesis Of One-Dimensional Nanomaterials And Their Applications In New Energy Systems

With the rapid development of modern industries and the durative increase of population, the rate of electrical energy consumption has dramatically increased and its consumption manner is diversified. Energy conversion and storage is becoming more and more important. Electricity can be generated from coal, wind, hydro, solar and other energy sources. Amoung various energy sources, solar energy has received much attention due to their outstanding advantages. Solar energy has many advantages, such as nontoxic, safe, pollution-free, low cost, without geographical restrictions and so on. Though solar energy has so much advanteges, it can be used in various electronic devices when it has been converted into electrical energy and stored. Developping advanced energy storage systems are also need to be put on the agenda. Among the various alternative energy storage technologies, Lithum ion batteries (LIBs) are the most important and widely used rechargeable battery with advantages of long cycling life, high energy density, low self-discharge, no memory effect, high voltage. Above all, both of solar cells and lithium-ion battery energy systems play important roles for electrical energy in practice use.Electrode materials are the key parts of solar cells and LIBs. Many factors, such as structure, morphology, specific, and surface area of the electrode materials influence the performance of solar cells and LIBs. Among various structures, One-dimensional (1D) nanostructures is thought as a distinguished alternative.1D nanostuctures is able to provide a direct pathway with less crystal boundaries for the rapid electron transport. In this thesis, several electrode materials with1D nanostuctures were successfully prepared and the electrochemical performance was investigated. ZnO arrays and Perovskite-type composite oxide have been considered as main objects. Ultralong porou ZnO nanobelt arrays and orderly gradient of CdS-CdSe assembled ZnO NW arrays were applied in dye-sensitized solar cells (DSSCs) and quantum-dot-sensitized solar cells (QDSSCs), respectively. SrSnO3nanorods and C@CaSnO3nanotubes were applied in LIBs, respectively. The effects of morphologies on the performance of solar cells and LIBs were investigated.1. Arrays of novel ultralong nanoporous ZnO nanobelts (NBs) are successfully synthesized and used as a photoanode in DSSC. Precursory ultralong ZnFOH NB arrays are firstly synthesized using a rapid hydrothermal method. The ZnFOH NB are aligned in a dense array with a length of32μm. Upon the subsequent pyrolysis of the ZnFOH precursor, ultralong nanoporous ZnO NB arrays were successfully generated. The structure of the products were characterized by SEM, TEM, HRTEM. Every NB is composed of a large number of nanocrystals and nanopores, which exhibit preferred orientation. DSSCs based on the ultralong porous ZnO NB arrays were assembled, and a high conversion efficiency (η) of3.28%for a27μm thick film was obtained at0.9suns.2. An orderly gradient of CdS-CdSe sensitized ZnO solar cell was designed. The bilayer configuration involves alternate cycles of nanowire growth and the orderly deposition of CdS and CdSe quantum dots (QDs) onto ZnO nanowire (NW). Such "rainbow" cell not only affords fast electron injection rate, but also increases the light harvesting. The bilayer assemblies have been used to fabricate QDSSCs which yield power conversion effiencies (η) of0.197much higher than that of ZnO/CdS based QDSSCs.3. SrSnO3nanorods are successfully synthesized and used as as anode in a LIB. Precursory SrSn(OH)6nanowires were successfully synthesized through a rapid simple methods-sonochemical synthesis at room temperature. The reaction conditions were carefully investigated. The experimental results revealed that both the ultrasound irradiation and the presence of Na2CO3in the synthetic process had an impact on the fast formation of the SrSn(OH)6nanowires. After a subsequent precipitations-hydrothermal treatment and a calcination process, SrSnO3nanorods were obtained. It was the first attempt to test the electrochemical properties of the SrSnO3products as anode in a LIB. The resulting SrSnO3nanorods exhibited a better cyclability over50cycles with a reversible lithium storage capacity of200mAh g-1than that of SrSnO3nanoparticles.4. Carbon-coated CaSnO3nanotubes (hereafter C-CTO NTs) are successfully synthesized and used as as anode in LIB. C-CTO NTs were directly obtained via a facile subsequent solvothermal synthesis using CaSn(OH)6nanotubes as precursor in a mixed ethanol and water solvent. Such an approach improves the high thermal stability of C-CTO NTs. The mixed solvent not noly facilitates the phase transformation of CaSnO3from CaSn(OH)6to take place quickly, but also retains the tube-shaped morphology. A thermal calcination process at650℃was followed to enhance the crystallinity of CaSnO3. When used as anode material in LIBs, the core-shell C-CTO NT electrode demonstrated improved and stable capacity values of about300mAh g-1with50cycles over CTO NT electrode and CaSnO3nanocube (CTO NC) electrode.