Lei Zu

Preparation and Electrochemical Characterization of Mesoporous Polyaniline-Silica Nanocomposites as an Electrode Material for Pseudocapacitors

Mesoporous polyaniline-silica nanocomposites with a full interpenetrating structure for pseudocapacitors were synthesized via the vapor phase approach. The morphology and structure of the nanocomposites were deeply investigated by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption-desorption tests. The results present that the mesoporous nanocomposites possess a uniform particle morphology and full interpenetrating structure, leading to a continuous conductive polyaniline network with a large specific surface area. The electrochemical performances of the nanocomposites were tested in a mixed solution of sulfuric acid and potassium iodide. With the merits of a large specific surface area and suitable pore size distribution, the nanocomposite showed a large specific capacitance (1702.68 farad (F)/g) due to its higher utilization of the active material. This amazing value is almost three-times larger than that of bulk polyaniline when the same mass of active material was used.

Ultra High Electrical Performance of Nano Nickel Oxide and Polyaniline Composite Materials

The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD) as the template agent. The experimental results revealed that the composite electrode processed a high specific capacitance (2122.75 F·g−1 at 0.1 A·g−1 in 0.05 M KI electrolyte solution), superior energy density (64.05 Wh·kg−1 at 0.2 A·g−1 in the two-electrode system) and excellent cycle performance (86% capacitance retention after 1000 cycles at 1.5 A·g−1). All those ultra-high electrical performances owe to the KI active material in the electrolyte and the PANI coated nano-NiO structure.

New Supercapacitors Based on the Synergetic Redox Effect between Electrode and Electrolyte

Redox electrolytes can provide significant enhancement of capacitance for supercapacitors. However, more important promotion comes from the synergetic effect and matching between the electrode and electrolyte. Herein, we report a novel electrochemical system consisted of a polyanilline/carbon nanotube composite redox electrode and a hydroquinone (HQ) redox electrolyte, which exhibits a specific capacitance of 7926 F/g in a three-electrode system when the concentration of HQ in H2SO4 aqueous electrolyte is 2 mol/L, and the maximum energy density of 114 Wh/kg in two-electrode symmetric configuration. Moreover, the specific capacitance retention of 96% after 1000 galvanostatic charge/discharge cycles proves an excellent cyclic stability. These ultrahigh performances of the supercapacitor are attributed to the synergistic effect both in redox polyanilline-based electrolyte and the redox hydroquinone electrode.

High performance of activated multi-walled carbon nanotube composite electrode in KI redox electrolyte

Abstract High performance electrodes for supercapacitor usually are achieved by compositing conductive and redox materials, the former such as multi-walled carbon nanotubes (MWCNTs), graphene, etc., provide the electrical double-layer capacitances that far less than pseudo-capacitances of the later (metal oxide, polyaniline, and so on). Here, carbonaceous composite electrode of MWCNTs and the redox electrolyte are combined into an electrochemical system for high synergetic effect of capacitance. MWCNT is activated by acid treatment and its structures are characterized by scanning electron microscope, X-ray diffraction, and Infrared spectroscopy analyses. The electrochemical measurements of resultant electrodes showed an excellent synergetic effect. The acid-activated MWCNTs electrode exhibited the maximum specific capacitance of 682 F/g in 0.2 M KI redox electrolytes, which is about 2–20 times larger than MWCNTs and its composite electrode in universal electrolyte without KI.

A shape memory polyurethane based ionic polymer–carbon nanotube composite

We report for the first time the fabrication of ionic polyurethane (IPU) based ionic polymer–carbon nanotube composite (IPCC) actuators. Graphene oxide (GO) was homogeneously dispersed in the IPU matrix to enhance the shape memory effect (SME) and action in terms of blocking force and displacement. Carbon nanotubes (CNTs) were used as the electrodes of the IPCC through a coating method. The blocking force of 25% GO–IPU was 7.8 gf g−1, it was 5 times that of neat IPU. Moreover, the shape memory recovery speed of the GO–IPU based IPCC was improved, from 3.2° s−1 for neat IPU to 4.5° s−1 for the composite membrane of 25% GO–IPU. The results indicated that the novel actuator showed both shape memory performance and electromechanical behavior and GO enhanced the functional properties in terms of SME and actuation.

Synthesis and Shape Memory Property of a MDI Based Liquid Crystalline Polyurethane

Liquid crystalline polyurethanes (LCPU) were prepared from 4,4’-methylenediphenyl diisocyanate (MDI), 1,6-hexanediol (HDO), 2,2-dimethylol propionic acid (DMPA) and polytetramethylene ether glycol (PTMG). The experiments synthesized three liquid crystalline polyurethane films with different soft/hard segment ratio. Chemical and structural characterization of the polyurethanes were investigated by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, differential scanning calorimeter and polarized microscopy respectively. Swelling rate and shape memory property were tested. The results indicated that the polyurethane with 62% soft segment and large group of carboxyl displayed excellent swelling and shape memory properties, and the shape recovery rate reached 100%. It was found that the crystallinity, thermal stability decreased and the temperature flexibility, water absorption and shape recovery rate increased with the increase of polytetramethylene ether glycol.

The preparation and characterisation of the high ordered Ga-SBA-15 with high gallium loading

Abstract The high gallium content and ordered mesoporous Ga-SBA-15 materials were prepared via a direct sol–gel hydrothermal approach. X-ray fluorescence, wide angle X-ray diffraction, nitrogen adsorption–desorption analysis, transmission electron microscopy, small-angle X-ray scattering and scanning electron microscopy are used to characterise the materials, and analysis of these results shows that the structure of these materials with different Si/Ga ratios is excellently ordered. Furthermore, the data of small-angle X-ray scattering and nitrogen adsorption–desorption analysis proved that the wall thickness of mesoporous Ga-SBA-15 materials was decreased by increasing the gallium content. Adsorption of xylene and hydroquinone over the different Si/Ga molar ratios of these materials was explored and the findings showed that SBA-15 did not perform as well.

Synthesis of polyaniline nanostructure with controlled morphology in mixed solvent

Abstract Nanostructured polyaniline was prepared using the template method in the mixed solvent that was composed of dimethyl formamide and distilled water. A series of tests were performed to examine the structural and electrical performance of polyaniline, including X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectrometry, nitrogen adsorption–desorption, cyclic voltammetry and galvanostatic charge–discharge tests. Results indicated that the mixed solvent could lead to a different morphology and influence the electrical performance of polyaniline in the system. The specific surface area of polyaniline was greatly improved and the electrical properties were enhanced correspondingly.

The Preparation and Characterization of the Mesoporous Poly(bisphenol-A carbonate) – Silica Nanocomposites

The mesoporous polycarbonate-silica nanocomposite materials were synthesized through the modified sol-gel approach under acidic condition. The specific surface area, pore diameter and pore volume of polycarbonate-silica could be controlled by changing the acidity of the synthesis system. The polycarbonate-silica possess an irregular block morphology according to the scanning electron microscopy observations. With decreasing the pH value of the synthesis system, the specific surface area and pore diameter of polycarbonate-silica were raised but the pore volume was reduced. The maximum specific surface area of polycarbonate-silica was 701.71m2/g which presented by the results of Nitrogen adsorptiondesorption isotherms.