Y.Q. Qiao

Multicolor electrochromic polyaniline–WO3 hybrid thin films: One-pot molecular assembling synthesis

Nanostructured polyaniline (PANI)–WO3 hybrid thin films were synthesized via a molecular assembling route in a solution of aniline using peroxotungstic acid (PTA) as the dopant and ammonium persulfate as the oxidant. The films show a porous morphology with nanorod arrays on the surface, and WO3 is uniformly incorporated into the polymer network. Electrochemical and electrochromic tests including cyclic voltammetry, chronoamperometry and corresponding in situ transmittance of PANI–WO3 hybrid films compared with neat PANI film and sol–gel WO3 film were conducted in 0.5 M sulfuric acid solution. The hybrid films, being a dual electrochromic material, varied from royal purple to green, pale yellow and finally dark blue as the applied potential was scanned from 0.8 V to −0.5 V. Compared to sulfate doped PANI film, high colouration efficiency and comparable durability are obtained in the PANI–WO3 hybrid films. The PANI–WO3 hybrid films also show faster switching speed and better durability than WO3 film. The enhanced electrochromic properties such as faster switching speed and better durability are mainly attributed to the combining of advantages of both materials and the formation of the donor–acceptor system.

Carbon‐Decorated Single‐Crystalline Ni2P Nanotubes Derived from Ni Nanowire Templates: A High‐Performance Material for Li‐Ion Batteries

Single-crystalline Ni(2)P nanotubes (NTs) were facilely synthesized by using a Ni nanowire template. The mechanism for the formation of the tubular structures was related to the nanoscale Kirkendall effect. These NTs exhibited a core/shell structure with an amorphous carbon layer that was grown in situ by employing oleylamine as a capping agent. Galvanostatic charge/discharge measurements indicated that these Ni(2)P/C NTs exhibited superior high-rate capability and good cycling stability. There was still about 310 mA h  g(-1) retained after 100 cycles at a rate of 5 C. Importantly, the tubular nanostructures and the single-crystalline nature of the Ni(2)P NTs were also preserved after prolonged cycling at a relatively high rate. These improvements were attributed to the stable nanotubular structure of Ni(2)P and the carbon shell, which enhanced the conductivity of Ni(2)P, suppressed the aggregation of active particles, and increased the electrode stability during cycling.

Synthesis of dinickel phosphide (Ni2P) for fast lithium-ion transportation: a new class of nanowires with exceptionally improved electrochemical performance as a negative electrode

Single-crystalline dinickel phosphide (Ni2P) nanowires with a uniform diameter of about 8 nm and lengths of 100–200 nm were synthesized from the thermal decomposition of continuously delivered Ni-TOP complexes using a syringe pump. These Ni2P nanowires deliver specific reversible capacities of 434 mA h g−1 at 0.1 C, 326 mA h g−1 at 0.5 C after 50 cycles, and also exhibit good rate performance. The improved electrochemical performance is attributed to the small size and stable cylindrical structure, which result in a high interfacial contact area with the electrolyte, and relieve the strain or accommodate volume expansion/contraction of these Ni2P nanowires. Electrochemical impedance spectra confirms that these Ni2P nanowires possess enhanced electrical conductivity, which facilitates the lithium ion and electron transportation in the electrode.