Qualtec Co.

Sakai, Japan

Qualtec Co.

Sakai, Japan
SEARCH FILTERS
Time filter
Source Type

Xu J.,Jiangsu Polytechnic University | Xu J.,Qualtec Co. | Gao L.,Jiangsu Polytechnic University | Cao J.,Jiangsu Polytechnic University | And 3 more authors.
Journal of Solid State Electrochemistry | Year: 2011

Nickel oxide (NiO) nanotubes for supercapacitors were synthesized by chemically depositing nickel hydroxide in anodic aluminum oxide templates and thermally annealing at 360 °C. The synthesized nanotubes have been characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The capacitive behavior of the NiO nanotubes was investigated by cyclic voltammetry, galvanostatic charge-discharge experiment, and electrochemical impedance spectroscopy in 6 M KOH. The electrochemical data demonstrate that the NiO nanotubes display good capacitive behavior with a specific capacitance of 266 Fg -1 at a current density of 0.1 Ag -1 and excellent specific capacitance retention of ca. 93% after 1,000 continuous charge-discharge cycles, indicating that the NiO nanotubes can become promising electroactive materials for supercapacitor. © Springer-Verlag 2010.


Xu J.,Jiangsu Polytechnic University | Xu J.,Qualtec Co. | Gao L.,Jiangsu Polytechnic University | Cao J.,Jiangsu Polytechnic University | And 3 more authors.
Electrochimica Acta | Year: 2010

Cobalt oxide (Co3O4) nanotubes have been successfully synthesized by chemically depositing cobalt hydroxide in anodic aluminum oxide (AAO) templates and thermally annealing at 500 °C. The synthesized nanotubes have been characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The electrochemical capacitance behavior of the Co3O4 nanotubes electrode was investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 6 mol L-1 KOH solution. The electrochemical data demonstrate that the Co3O4 nanotubes display good capacitive behavior with a specific capacitance of 574 F g -1 at a current density of 0.1 A g-1 and a good specific capacitance retention of ca. 95% after 1000 continuous charge-discharge cycles, indicating that the Co3O4 nanotubes can be promising electroactive materials for supercapacitor. © 2010 Elsevier Ltd. All rights reserved.


Xu J.,Changzhou University | Xu J.,Qualtec Co. | Dong Y.,Changzhou University | Dong Y.,Qualtec Co. | And 5 more authors.
Electrochimica Acta | Year: 2013

Urchin-like Ni(OH)2-Co(OH)2 hollow microspheres were successfully synthesized by a microwave-incorporated hydrothermal method. The Ni(OH)2-Co(OH)2 hollow microspheres achieved a high specific capacitance of 2164 F g-1 at 1 A g-1 and long-term cycle life. Electrochemical data reveal that the Ni(OH) 2-Co(OH)2 hollow microspheres exhibits much better electrochemical reversibility and specific capacitance retention than that of the single Ni(OH)2 or Co(OH)2 based on peak potential difference, symmetry of charge-discharge curves, and specific capacitances at high charge-discharge rates. Furthermore, the designed Ni(OH) 2-Co(OH)2/graphene asymmetric supercapacitor displays good reversibility and a high specific capacitance of 169 F g-1 at 1 A g-1, 145 F g-1 at 3 A g-1, and 116 F g -1 at 5 A g-1, indicating a good ability to deliver a high energy density at a high power density. These results proved that the Ni(OH)2-Co(OH)2 hollow microspheres can be promising electroactive materials for supercapacitor and the microwave-incorporated hydrothermal method provided a one-step, template-free, and cost-effective route for fabricating pseudocapacitive materials in 3-D form. © 2013 Elsevier Ltd. All rights reserved.


Wang Y.,Changzhou University | He J.,Changzhou University | Wang W.,Changzhou University | Shi J.,Changzhou University | And 2 more authors.
Applied Surface Science | Year: 2014

The preparation of Ni-P/Ni3.1B composite alloy coating on the surface of copper was achieved by co-deposition of Ni3.1B nanoparticles with Ni-P coating during electroless plating. Ni-P-B alloy coating was obtained by heat-treating the as-plated Ni-P/Ni3.1B composite coating. The effect of the concentration of sodium alginate, borax, thiourea, Ni3.1B, temperature, and pH value on the deposition rate and B content were investigated and determined to be: 30 g L-1, 10 g L -1, 2 mg L-1, 20 mg L-1, 70 C and 9.0, respectively. Sodium alginate and thiourea were played as surfactant for coating Ni3.1B nanoparticles and stabilizer for the plating bath, respectively. Ni-P/Ni3.1B composite coating had good performance such as corrosion resistance and solderability. © 2013 Elsevier B.V.


Xu J.,Changzhou University | Xu J.,Qualtec Co. | Meng R.,Changzhou University | Cao J.,Changzhou University | And 6 more authors.
Journal of Alloys and Compounds | Year: 2013

The hydrogen release properties of the graphene supported Pd (Pd-G) catalysts doped LiBH4 were systematically investigated. It was found that the onset hydrogen desorption temperature of the LiBH4 doped with 5 wt.% Pd-G-60 (with 60 wt.% Pd loading) catalyst was about 105 C lower than that of the pure LiBH4 milled under the same conditions, and the other main dehydrogenation peaks of the Pd-G-60 doped LiBH4 were shifted to 410 and 605 C with an increased total weight loss of 12.6 wt.%. Moreover, the dehydrogenation enthalpy was reduced from 74 kJ mol-1 H2 for the pure LiBH4 to ca. 43 kJ mol-1 H 2 for the 15 wt.% Pd-G-60 doped LiBH4. Importantly, the reversible rehydrogenation process was achieved under 3 MPa H2 at 400 oC for 10 h, and a capacity of ca. 6.6 wt.% was obtained in the 30th cycle, which should be attributed to the evenly dispersed Pd nanoparticles. Meanwhile, LiBH4 was reformed and one new product, B 16H20, was detected after the rehydrogenation process.© 2013 Elsevier B.V. All rights reserved.


Xu J.,Changzhou University | Xu J.,Qualtec Co. | Li Y.,Changzhou University | Cao J.,Changzhou University | And 4 more authors.
Catalysis Science and Technology | Year: 2015

Using a hydrogen thermal reduction method, highly dispersed nickel nanoparticles (ca. 9.7 nm) were uniformly supported on graphene (Ni/G), and then ball-milled with LiBH4 to investigate in depth their hydrogen storage behaviour. The Ni/G-doped system exhibited high gravimetric hydrogen capacity, excellent rehydrogenation reversibility and rapid kinetics, due to the synergistic effect of nanoconfinement in graphene and catalysis by Ni nanoparticles, demonstrating a promising strategy for the effective design of hydrogen storage materials using LiBH4. In the case of doping with 20 wt.% Ni/G, thermal dehydrogenation of LiBH4 began around 180 °C, and the main hydrogen release peaks occurred at 275 and 465 °C, with a total weight loss of 15.2 wt.%. At 450 °C, about 12.8 wt.% hydrogen was desorbed in 45 min. More importantly, the hydrogen released during a second dehydrogenation remained at 12.6 wt.%, and a steady hydrogen capacity of ca. 9.8 wt.% was achieved during the thirtieth hydrogen uptake-release cycle under 3 MPa H2 at 400 °C, demonstrating the effectiveness of the Ni/G catalyst in the reversibility of hydrogen uptake of LiBH4 at relatively lower temperatures and pressure. During this process LiBH4 was re-formed and a new product, Li2B12H12, was detected following rehydrogenation. © 2015 The Royal Society of Chemistry.


Zhang Q.,Changzhou University | Wang Y.,Changzhou University | Wang W.,Changzhou University | Mitsuzak N.,Qualtec Co. | Chen Z.,Changzhou University
Electrochemistry Communications | Year: 2016

Diamond-like carbon (DLC) films are prepared by electrodeposition technique on SnO2-coated glass substrates in chloroacetic acid aqueous solution. The applied voltage between the electrodes is mere 3.0 V for 2 h. The films composed of small and compact grains that show two distinct Raman characteristic peaks at ~ 1340 and ~ 1580 cm- 1. With the method reported in this paper, the DLC films are firstly fabricated the DLC films at both low voltage and ambient temperature. © 2015 Elsevier B.V.All rights reserved.


Xu J.,Changzhou University | Xu J.,Qualtec Co. | Wei X.,Changzhou University | Cao J.,Changzhou University | And 6 more authors.
Electrochimica Acta | Year: 2015

Graphene/acetylene black sandwich film was fabricated by a simple vacuum filtration procedure using a stable complex suspension of graphene oxide (GO) and acetylene black followed by a hydroiodic acid (HI) immersion process to fully reduce the GO to graphene sheets. The self-restacking of individual graphene sheets were greatly alleviated and electric conductivity was obviously improved using the acetylene black nanoparticles as both effective spacers to expand the inter-layer interval of the individual graphene sheets during the film assembly course and highly conducting bridges to facilitate the electron/ion transfer between the upper and lower graphene sheets. The flexible graphene/acetylene black film was utilized as supercapacitor electrode without additional conductive additives, binders and current collectors, which achieved an obviously higher specific capacitance (ca. 136.6 F g-1 at 0.5 A g-1) and much better specific capacitance retention at high current densities than that of the pure graphene film electrode, indicating that such a novel sandwich film structure allows for a higher charge storage capability. More importantly, the assembled symmetric supercapacitor device displayed a satisfactory specific capacitance of 59.2 F g-1 at 0.1 A g-1, 47.6 F g-1 at 0.5 A g-1 and 42.8 F g-1 at 1 A g-1, and only negligible 4.05% capacitance degradation have been found after 1000 continuous charge-discharge cycles at 0.5 A g-1, revealing outstanding rate capability, excellent electrochemical reversibility and long-term cyclability. These results proved that such a flexible and highly conductive graphene/acetylene black film can be promising electroactive materials in the development of advanced electrochemical energy storage devices. © 2014 Elsevier Ltd.


Shimizu M.,Kyoto University | Sakakura M.,Kyoto University | Ohnishi M.,Qualtec Co. | Shimotsuma Y.,Kyoto University | And 3 more authors.
Journal of Applied Physics | Year: 2010

Accumulation of thermal energies by highly repeated irradiation of femtosecond laser pulses inside a glass induces the heat-modification whose volume is much larger than that of the photoexcited region. It has been proposed that the heat-modification occurs in the region in which the temperature had overcome a threshold temperature during exposure of laser pulses. In order to understand the mechanism of the heat-modification, we investigated the temperature distribution during laser exposure and the threshold temperature by analyzing the volume of the modification based on a thermal diffusion model. We found that the threshold temperature becomes lower with increasing laser exposure time. The dependence of the threshold temperature on the laser exposure time was explained by the deformation mechanism based on the temperature-dependent viscosity and viscoelastic behavior of a glass under a stress loading by thermal expansion. The deformation mechanism also could simulate a tear-drop shape of a heat-modification by simultaneous double-beams' irradiation and the distribution of birefringence in a heat-modification. The mechanism proposed in this study means that the temperature-dependence of the viscosity of a glass should be essential for predicting and controlling the heat-modification. © 2010 American Institute of Physics.


Trademark
QualTec LLC | Date: 2015-10-06

Chemical preparations for use in the car wash industry and industrial chemicals.

Loading Qualtec Co. collaborators
Loading Qualtec Co. collaborators