No abstract

Zinc oxide (ZnO) is one of the most promising metal oxide semiconductor materials, particularly for optical and gas sensing applications. The influence of thickness and solvent on various features of ZnO thin films deposited at ambient temperature and barometric pressure by the sequential ionic layer adsorption and reaction method (SILAR) was carefully studied in this work. Ethanol and distilled water (DW) were alternatively used as a solvent for preparation of ZnO precursor solution. Superficial morphology, crystallite structure, optical and electrical characteristics of the thin films of various thickness are examined applying X-ray diffraction (XRD) system, scanning electron microscopy, the atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, photoluminescence spectroscopy, Hall effect measurement analysis and UV response study. XRD analysis confirmed that thin films fabricated using ethanol or DW precursor solvents are hexagonal wurtzite ZnO with a preferred growth orientation (002). Furthermore, it was found that thin films made using ethanol are as highly crystalline as thin films made using DW. ZnO thin films prepared using aqueous solutions possess high optical band gaps. However, films prepared with ethanol solvent have low resistivity (10–2 Ω cm) and high electron mobility (750 cm2/Vs). The ethanol solvent-based SILAR method opens opportunities to synthase high quality ZnO thin films for various potential applications.

Sulfur/dehydrogenated polyacrylonitrile/ketjen black (S/DPAN/KB) flexible nanofiber composite was prepared by electrospinning technique and tested as a freestanding cathode for high-performance flexible lithium/sulfur batteries. S/PAN/KB was dehydrogenated at 300 • C without carbonizing and used as a cathode without any binder/current collector. The SEM observations of the obtained S/DPAN/KB nanofibers showed that the fiber diameters were in a range of 300-600 nm and the sample had a rough surface due to the presence of the S/KB particles. According to the SEM/EDS analysis sulfur is uniformly distributed within PAN fibers in both S/PAN/KB and S/DPAN/KB (heat treated) composites. The prepared binder-free S/DPAN/KB composite cathode exhibited a good electrochemical performance delivering a reversible capacity of 917 mAh g −1 after 150 cycles, exhibiting a coulombic efficiency about 100%, and demonstrating stable cyclability and good rate capability with a reversible capacity of 342 mA h g −1 at 1 C. The obtained composite cathode is highly flexible and can be used for LIB powering flexible electronic devices.

This review article focuses on methods to solve a critical issue of reduction in NASICON-type solid electrolytes such as Li1+xAlxTi2-x(PO4)3 and Li1+xAlxGe2-x(PO4)3 by Li metal. The formation of reduced phase...