Study On Synthesis, Characterization And Devices Of Hierarchical Nanowires

Based on hierarchical nanowires, in order to explore and push the limitation of hierarchical nanowire structures to a higher level, hierarchical vanadium oxide nanowires constructed by attached solid nanorods, hierarchical La-Sr-Co-O nanowires constructed by oriented mesoporous nanorods, and hierarchical single-crystalline kinked silicon nanowires were designed and synthesized followed by characterization and device applications. The following interesting results were achieved:(1) Hierarchical vanadium oxide nanowiresUltralong hierarchical "rod-in-wire" vanadium oxide nanowires constructed by attached solid V2O5nanorods were designed and synthesized by electrospinning. The ultralong hierarchical vanadium oxide nanowires can inhibit self-aggregation of nanomaterials, and greatly improve the performance of lithium ion battery electrode materials with average specific capacity of300mAh/g. Solid single nanowire lithium ion battery was designed and fabricated for the first time, and we explored the direct relation between electrical transport, structure, and electrochemical performance of a single nanowire electrode through in situ characterization, probing the insintric reason for battery capacity fading.(2) Hierarchical mesoporous La-Sr-Co-O nanowiresHierarchical mesoporous perovskite La-Sr-Co-O (LSCO) nanowires constructed by oriented attached mesoporous nanorods were synthesized using a multistep microemulsion self-assembly method. It was demonstrated that the hierarchical mesoporous LSCO nanowires are high-performance catalysts for the oxygen reduction reaction (ORR) with low peak-up potential and high limiting diffusion current. The lithium air batteries using hierarchical mesoporous LSCO nanowires as the catalyst were fabricated and exhibit very high specific capacity more than11000mAh/g, which is improved by one order of magnitude compared to LSCO nanoparticles.(3) Hierarchical single-crystalline kinked silicon nanowiresDiverse single-crystalline silicon polygon nanorings and probe-like kinked nanowires were synthesized using gold-nanoparticle catalyzed chemical vapor deposition, in which polygon nanorings include hexagonal, triangular, rhombic and trapezoidal nanorings, while probe-like kinked nanowires include U-shape, V-shape and W-shape kinked nanowires. Furthermore, U-shape and V-shape kinked NWs were assembled at well-defined positions and with highly controlled orientation by rationally designed micropillar array. Three-dimensional single kinked silicon nanowire bend-up bioprobes were designed and fabricated followed by electrical characterization such as conductance and transconductance. W-shape single kinked silicon nanowire bend-up bioprobes were used to simultaneously measure the signals (such as action potential) at different regions of the rat cardiomyocytes.