Papers by Author: Ai Ping Jin

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: Charged Au nanoparticles with various diameters, from 2.7 nm to 10.3 nm, were synthesized by using various reducing agents. Then charged Au nanoparticles were self-assembled onto the NafionTM membrane surface as methanol barriers. It was found that the proton exchange membrane self-assembled with 3.9 nm Au particles had the lowest methanol crossover. The proton conductivity decreased with the increase of the particles size until the particles size was more than 6.2 nm and they had little influence on the membrane conductivity. All the self-assembled membranes have higher open circuit voltage (OCV) and performance than original Nafion212TM membrane. And the membranes self-assembled with 3.9 nm poly (diallymethylammonium chloride) (PDDA) modified Au (PDDA-Au) particles had the highest performance due to the reciprocal of the methanol permeation current density and membrane area resistance.

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.