Advanced Materials Technology Center

Singapore, Singapore

Advanced Materials Technology Center

Singapore, Singapore
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Jin L.,Advanced Materials Technology Center | Jin L.,Guangdong University of Technology | Zhang H.,Guangdong University of Technology | Ping L.,Advanced Materials Technology Center | And 2 more authors.
IEEE Transactions on Electromagnetic Compatibility | Year: 2014

A low-cost and transparent stainless steel fiber (SSF)/silicone resin composite was prepared by blending shortcut SSF with silicone resins. The SSF was homogeneously dispersed in resins at submicrometer scales and formed cross-linking structures. The visible light transmittance (VLT) and shielding effectiveness (SE) of composite in the frequency range of 300 MHz-1.5 GHz were investigated, and the result showed that the VLT was 70%, while the SE was 15-26 dB and the VLT was 67%, while the SE was 27-36 dB at 1.00 wt.% and 1.25 wt.% SSF concentrations, respectively. The result suggested that SSF/silicone resin composite may be useful for electromagnetic interface shielding application, especially when there is a visibility requirement. The shielding mechanism was investigated by quantitatively studying the absorbed and reflected energy to the total SE, and the result revealed that the dominant shielding mechanism of SSF/silicone resin composite was reflection loss. © 1964-2012 IEEE.

Liu L.,National University of Singapore | Yang Z.H.,National University of Singapore | Kong L.B.,National University of Singapore | Li P.,Advanced Materials Technology Center
IEEE Transactions on Electromagnetic Compatibility | Year: 2012

Novel flexible transparent composite sheets were fabricated with glass-coated nanocrystalline ferromagnetic microwires and transparent silicone matrix. The free-space method was employed to measure the effective permittivity and shielding effectiveness (SE) of samples fabricated from 4 to 20 GHz. SE of the transparent shielding layer with 1wt of microwires and thickness of 0.85 mm can be more than 20 dB when frequency is above 11 GHz. Due to resonance phenomena of the embedded shortcut microwires with a length of about 5 mm, both dielectric permittivity and loss of the composite are quite high at microwave frequency. Hence, such transparent composite sheets may also find applications in microwave applications © 2006 IEEE.

Hu G.,National University of Singapore | Li C.,Advanced Materials Technology Center | Gong H.,National University of Singapore
Journal of Power Sources | Year: 2010

Nanoporous nickel hydroxide Ni(OH)2 coated on nickel foam by using a chemical bath deposition method shows a high specific capacitance of 2200 F g-1 at a discharging current density of 1 Ag-1. After 500 charge-discharge cycles, the specific capacitance is stabilized at 1470 Fg-1, and there is only a 5% fall in specific capacitance during the following 1500 cycles. The relationship between the capacitance decay and changes in the microstructure and morphology of nanoporous Ni(OH)2 is investigated. The results show that phase transformation and the growth of particle/crystal size, rather than the formerly proposed flaking off of Ni(OH)2, are the major factors contributing to the capacitance decay. © 2010.

Zhao F.,Center for Biomedical and Life science | Zhao F.,Advanced Materials Technology Center | Lee C.-L.K.,Center for Biomedical and Life science | Kwan W.L.,Advanced Materials Technology Center
Solar Energy Materials and Solar Cells | Year: 2011

Spray coating is a high throughput coating technique that is scalable and adaptable for organic photovoltaic manufacturing. To ensure uniform coating of the organic layers, the wettability, surface tension and boiling points of the solvents have to be optimized. Here, we used microscopic videos to understand the dynamics of the spray coating process. By optimizing the wettability and drying time of the PEDOT:PSS suspension on a hydrophobic surface, we attained a spray coated transparent anode without compromising on device performance. We further applied this vacuum-free process to a near infrared absorber to achieve a transparent organic solar cell with close to 60% transparency. © 2011 Elsevier B.V. All rights reserved.

He J.,East China University of Science and Technology | Hua J.,East China University of Science and Technology | Hu G.,National University of Singapore | Yin X.J.,Advanced Materials Technology Center | And 2 more authors.
Dyes and Pigments | Year: 2014

Four novel carbazole organic dyes containing either a furan or a thiophene unit as the conjugated bridge have been designed, synthesized and characterized for nanocrystalline TiO2 dye-sensitized solar cells. The modified carbazole containing linear or branched alkyl side chain acts as an electron donor, triphenylamine acts as an electron-donating group and cyanoarylic acid acts as an electron acceptor and anchoring unit. The absorption spectra, electrochemical, photovoltaic and sensitizing properties of the new dyes were fully characterized. Among these four dyes, the dye incorporating an octyl-substituted carbazole and disubstituted furan shows the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency of 92.4%, a short-circuit photocurrent density of 13.26 mA cm -2, an open-circuit photovoltage of 724 mV, and a fill factor of 0.66, corresponding to an overall conversion efficiency of 6.68% under standard global AM 1.5 solar light condition. The results indicate that the introduction of longer alkyl chain into the carbazole moiety will retard recombination and the introduction of furan as the conjugate bridge will increase the photocurrent response. For comparison, the ruthenium dye, designated as N719, sensitized TiO2 solar cell showed an efficiency of 6.98% under the same experiment conditions. © 2014 Elsevier Ltd. All rights reserved.

Hu G.,National University of Singapore | Tang C.,National University of Singapore | Li C.,Advanced Materials Technology Center | Li H.,National University of Singapore | And 2 more authors.
Journal of the Electrochemical Society | Year: 2011

Nickel cobalt (Ni-Co) oxides with various Ni/Co ratios are synthesized by using a sol-gel process. Electrochemical performance, microstructure, morphology and BET surface area are found strongly related to Ni and Co concentration. Increasing Co concentration changes the oxide microstructure from NiO crystal dominate structure (Ni:Co 1:1 and 1:2) to Co3O4 dominate structure (Ni:Co 1:4 and 0:1). A maximum specific capacitance of 1539 Fg -1 was obtained for Ni-Co (Ni:Co 1:2) oxide at a current density of 1Ag-1, and this capacitance is similar to that of RuO2. A systematic study shows that the Ni-Co oxide (1:2) has a mesoporous structure with a high BET surface area of ∼ 315 m2 g-1 and porous size of ∼ 4.7 nm, which is favorable for the charge/dischargeprocess of a supercapacitor. © 2011 The Electrochemical Society.

Nguyen V.N.,Vietnam National University, Hanoi | Nguyen T.D.C.,Quy Nhon University | Dao T.P.,Vietnam National University, Hanoi | Tran H.T.,Advanced Materials Technology Center | And 2 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2013

Organoclays were synthesized by exchanging inorganic cations between layers in Thanh Hoa bentonite using organic cations including benzylhexadecyldimethylammonium (BHDDM+), dimethyldioctadecylammonium (DMDOD+) and benzylstearyldimethylammonium (BSDM+). Inserting organic cations increases material interlayer distance significantly (from 15Å to 40Å) and simultaneously enhances affinity of materials toward organic pollutants. The results show that adsorption capacity of organics on organoclays strongly depends on affinity between organic substances and ammonium cations rather than on interlayer distance of organoclays. This means that the sorption of organoclays for organic contaminants was significantly influenced by the nature of the surfactants added to the clay. © 2012 The Korean Society of Industrial and Engineering Chemistry.

Zhang D.,East China Normal University | Zhang D.,Advanced Materials Technology Center | Li X.,East China Normal University | Chen S.,East China Normal University | And 3 more authors.
Microchimica Acta | Year: 2011

Double-wall carbon nanotubes (DWCNTs), single-wall carbon nanotubes (SWCNTs), and multi-wall carbon nanotubes (MWCNTs) were investigated as an alternative for platinum in counter-electrodes for dye-sensitized solar cells. The counter-electrodes were prepared on fluorine-doped tin oxide glass substrates by the screen printing technique from pastes of carbon nanotubes and organic binder. The solar cells were assembled from carbon nanotubes counter-electrodes and screen printed anodes made from titanium dioxide. The cells produced with DWCNTs, SWCNTs or MWCNTs have overall conversion efficiencies of 8.0%, 7.6% and 7.1%, respectively. Electrochemical impedance spectroscopy measurements revealed that DWCNTs displayed the highest catalytic activity for the reduction of tri-iodide ions. The large surface area and superior chemical stability of the DWCNTs facilitated the electron-transfer kinetics at the interface between counter-electrode and electrolyte and yielded the lowest transfer resistance, thereby improving the photovoltaic activity. A short-term stability test at moderate conditions confirmed the robustness of solar cells based on the use of DWCNTs, SWCNTs or MWCNTs. © 2011 Springer-Verlag.

Zhang D.W.,East China Normal University | Zhang D.W.,Advanced Materials Technology Center | Li X.D.,East China Normal University | Li H.B.,East China Normal University | And 4 more authors.
Carbon | Year: 2011

Graphene nanosheets (GNs) were synthesized and used as a substitute for platinum as counter-electrode materials for dye-sensitized solar cells (DSSCs). The as-synthesized GNs were dispersed in a mixture of terpineol and ethyl cellulose. GN films were screen-printed on fluorine- doped tin oxide (FTO) slides using the formed GN dispersions. GN counter-electrodes were produced by annealing the GN films at different temperatures. The annealed GN films revealed an unusual 3D network structure. Structural and electrochemical properties of the formed GN counter-electrodes were examined by field emission scanning electron microscopy, Raman spectroscopy and electrochemical impedance spectroscopy. It was found that the annealing temperature of GN materials played an important role in the quality of the GN counter-electrode and the photovoltaic performance of the resultant DSSC. The grown DSSCs with graphene-based counter-electrodes exhibited a conversion efficiency high up to 6.81%. © 2011 Elsevier Ltd. All rights reserved.

Zhang D.W.,East China Normal University | Li X.D.,East China Normal University | Chen S.,East China Normal University | Tao F.,East China Normal University | And 3 more authors.
Journal of Solid State Electrochemistry | Year: 2010

Double-walled carbon nanotubes (DWCNTs) have been studied for counter-electrode application in dye-sensitized solar cells (DSCs). Mesoporous TiO2 films are prepared from the commercial TiO2 nanopowders by screen-printing technique on optically transparent-conducting glasses. A metal-free organic dye (indoline dye D102) is used as a sensitizer. DWCNTs are applied to substitute for platinum as counter-electrode materials. Morphological and electrochemical properties of the formed counter electrodes are investigated by scanning electronic microscopy and electrochemical impedance spectroscopy, respectively. The electronic and ionic processes in platinum and DWCNT-based DSCs are analyzed and discussed. The catalytic activity and DSC performance of DWCNTs and Pt are compared. A conversion efficiency of 6.07% has been obtained for DWCNT counter-electrode DSCs. This efficiency is comparable to that of platinum counter-electrode-based devices. © Springer-Verlag 2009.

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