Papers by Author: Quan Yao Zhu

Abstract: The hybrid guest-host nanocomposite films based on poly (ethylene oxide) (PEO) and molybdenum doped vanadium pentoxide (V_0.975Mo_0.025)₂O₅nH₂O were prepared by sol-gel and hydrothermal reaction via a two-part process. The electrical properties along and across V-O layers have been evaluated. The results indicate that the proper amount of PEO can increase the electrical conductivity of the films. The electrochromism of the films were investigated by cyclic voltammetry, the ex-situ transmission spectra and photographs. The films display a reversible multichromism (orangegreenbluebrown) upon Li⁺ ion insertion/extraction.

Abstract: Vanadium oxide/carbon nanotubes (VOx/CNTs) composites were prepared by sol-gel hydrothermal synthesis. The composites were characterized in terms of surface morphology and structure using SEM, TEM, XRD, FT-IR, respectively. The electrochemical behaviors of the composites were investigated by means of galvanostatic charge-discharge cycling. The result shows that the vanadium oxides nanotubes and carbon nanotubes contacted each other and the composites have great cycleability as well as capacity characteristics which arrived at 303.5 mAh/g in the first discharge process and 200.4 mAh/g after 50th discharge cycles.

Abstract: The cross-linked polystyrene prepolymer was synthesized with divinylbenzene (DVB) as crosslinker via free-radical crosslinking copolymerization (FCC) and used as the matrix materials for E-glass fiber reinforced composites. The surface modification was performed by treatment of E-glass fiber with γ-methacryloylpropyl trimethoxysilane (MPS) solution. Fourier transform infrared spectroscopy (FTIR) was used to identify the functional groups on the surface modified glass fibers. Dynamic mechanical thermal analysis (DMTA) of these composites revealed that the dynamic storage modulus (E′) was gradually enhanced with the increasing content of DVB (0~3.0 wt %) whereas the damping parameter (tanδ) peaks are lower and broader, indicating better load bearing capacity. Moreover, the Tg was shifted to higher temperature corresponding to the increasing of crosslinking density. Morphology of fracture surfaces for these composites showed different fiber-matrix interfacial adhesion which was mainly attributed to the variation of crosslinking network structure in the interface.

Abstract: Molybdenum doped vanadium oxide (Mo doped V2O5) xerogel films were prepared by cathodic electrodeposition on indium tin oxide (ITO) substrate from Mo doped V2O5 sol synthesized by sol-gel combined with hydrothermal reaction. Mo doped V2O5 xerogel films were deposited at different potentials between -0.01 V and -0.7 V vs saturated calomel electrode (SCE) with the potentiostatic mode. The structure was characterized for using X-ray diffraction (XRD), atomic force microscopy (AFM). These studies reveal that films consist of layered V2O5 host structure with various surface morphologies depending upon the deposition potentials. As shown by the cyclic voltammograms results, the films electrodeposited at -0.3 V exhibited Li+-ion storage capacity as high as ca. 70 mC/cm2 for the 50th cycle and showed multi-electrochromic behavior (orangered-green-blue) depending on the extent of intercalation during the electrochemical lithium insertion/extraction processes. It is proposed that the particles forming the films arrange directionally and crystallize partly, which lead to the enhanced electroactivity of vanadium oxide films by shortening the diffusion distance or quickening the transference rate of Li+ ions in the films.

Abstract: Vanadium pentoxide xerogel films intercalated by poly (ethylene oxide), PEO, were prepared using direct intercalation method via a sol-gel route. The electrical and electrochromic characterization of the films were conducted. The electrical properties along and across V-O layers have been evaluated. The results indicate that the proper amount of PEO can increase the electrical conductivity and charge density of the films. The electrochromism of the films upon lithium intercalation was investigated by ex-situ transmittance measurement. The films display a reversible multichromism (orange
green
blue) upon Li+ ion insertion/extraction.