Publications (15)40.65 Total impact
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Article: Shape Evolution and Magnetic Properties of Cobalt Sulfide
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ABSTRACT: In this work, well-defined uniform octahedrons of Co3S4 are synthesized via a simple biomolecule-assisted hydrothermal process for the first time. Evolution of the crystal-structure and the shape of the samples are examined systematically by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The formation mechanism of the octahedral Co3S4, possibly due to a ripening-splitting crystal growth process, and the effect of microstructure and morphology on their physical properties are investigated. This work may not only render a simple approach to synthesize highly symmetric, microstructured materials but also could provide fundamental insights of the effect of crystal structure transformation on physical properties.09/2008; -
Article: Template-Free Electrochemical Synthesis of Superhydrophilic Polypyrrole Nanofiber Network
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ABSTRACT: In this work, a superhydrophilic polypyrrole (PPy) nanofiber network is electrochemically synthesized in an aqueous solution by using phosphate buffer solution (PBS) in the absence of templates, surfactants and structure-directing molecules. FESEM, X-ray diffraction, UV−visible absorption, and contact angle measurement were employed to characterize the nanofiber network. The effect of synthetic conditions including pH, oxidation potential and concentrations of phosphate, pyrrole (Py) and dopant ClO4− on the PPy nanostructure is systematically investigated. A mechanism for the nanofiber formation in an aqueous solution without assistance of any “hard” and “soft” template is proposed, in which the presence of the hydrogen bonding between phosphate and Py oligomers is essential to producing the 1D nanofiber structure, and the electrostatic interactions between ion dopant and Py oligomers lead to an irregular nanostructure. This is a simple, environmentally friendly and one-step approach to fabricate a PPy film with unique nanostructure and chem-physical properties, which can have great potential in various applications such as sensors, electronics, and energy source systems.09/2008; -
Article: Well-Aligned Cone-Shaped Nanostructure of Polypyrrole/RuO2 and Its Electrochemical Supercapacitor
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ABSTRACT: A new well-aligned cone-shaped nanostructure of polypyrrole (WACNP) has been successfully grown on Au substrate by using a simple, one-step, reliable, and template-free anodic deposition method. The formation mechanism of WACNP is proposed, in which the hydrogen bonding introduced from phosphate buffer solution (PBS) promotes the formation of a well-aligned nanostructure of polypyrrole (PPy), while the steric hindrance effect arisen from high concentration of pyrrole (Py) boosts its vertical alignment and further forms a cone-shaped nanostructure. The 3D, arrayed, nanotubular architecture coated with an ultrathin layer of RuO2 by the magnetron sputtering deposition method was tailored to construct a supercapacitor. The unique structure and design not only reduces the diffusion resistance of electrolytes in the electrode material but also enhances its electrochemical performance. The modification of RuO2 on WACNP results in a capacitance higher than that of WACNP by three times. The specific capacitance of RuO2/WACNP is 15.1 mF cm−2 (302 F g−1) measured by the charge−discharge method with an applied current density of 0.5 mA cm−2 over a potential range of −0.2 to 0.7 V, and is greater than that of commercial carbon materials by 2−3 orders of magnitude. The high capacitance and good stability of the RuO2/WACNP electrode is very promising for applications in microsupercapacitor devices.08/2008; -
Article: Direct electrochemistry and electrocatalytic mechanism of evolved Escherichia coli cells in microbial fuel cells.
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ABSTRACT: E. coli cells evolved under electrochemical tension in a microbial fuel cell possess direct electrochemical behavior due to the excretion of hydroquinone derivatives through a highly permeable outer membrane, and their catalyzed fuel cell demonstrates excellent performance.Chemical Communications 04/2008; · 6.17 Impact Factor -
Article: Nanostructured polyaniline/titanium dioxide composite anode for microbial fuel cells.
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ABSTRACT: A unique nanostructured polyaniline (PANI)/mesoporous TiO(2) composite was synthesized and explored as an anode in Escherichia coli microbial fuel cells (MFCs). The results of X-ray diffraction, morphology, and nitrogen adsorption-desorption studies demonstrate a networked nanostructure with uniform nanopore distribution and high specific surface area of the composite. The composite MFC anode was fabricated and its catalytic behavior investigated. Optimization of the anode shows that the composite with 30 wt % PANI gives the best bio- and electrocatalytic performance. A possible mechanism to explain the excellent performance is proposed. In comparison to previously reported work with E. coli MFCs, the composite anode delivers 2-fold higher power density (1495 mW/m(2)). Thus, it has great potential to be used as the anode for a high-power MFC and may also provide a new universal approach for improving different types of MFCs.ACS Nano 02/2008; 2(1):113-9. · 10.77 Impact Factor -
Article: Synthesis and electrical transport of novel channel-structured beta-AgVO3.
Small 08/2007; 3(7):1174-7. · 8.35 Impact Factor -
Article: Mesoporous amorphous MnO2 as electrode material for supercapacitor
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ABSTRACT: A kind of novel mesoporous, electrochemical active material, amorphous MnO2 has been synthesized by an improved reduction reaction and using supramolecular as template. The synthesized sample was characterized physically by thermogravimetric analysis, X-ray diffraction, transmission electron microscope (TEM), and Brunauer–Emmett–Teller (BET) surface area measurement, respectively. Electrochemical characterization was performed using cyclic voltammetry and chronopotentiometry in 2mol/l KOH aqueous solution electrolyte. The results of BET and TEM analysis indicated that supramolecular template plays an important role in the process of big specific surface area mesoporous material forming. After sintering at 200°C, the sample still remained an amorphous structure, and its specific capacitance reached 298.7F/g and presented a very stable capacitance after 500 cycles. In addition, the electrochemical process, such as ion transfer and electrical condition, was also investigated with electrochemical impedance spectroscopy.Journal of Solid State Electrochemistry 01/2007; 11(8):1101-1107. · 2.13 Impact Factor -
Article: Nanocrystalline nickel cobalt hydroxides/ultrastable Y zeolite composite for electrochemical capacitors
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ABSTRACT: A novel nanocomposite of Co(OH)2−Ni(OH)2 and ultrastable Y molecular sieves was synthesized by an improved chemical precipitation method for electrochemical capacitors. The Co(OH)2−Ni(OH)2/ultrastable Y zeolite (USY) composite and its microstructure were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Electrochemical characterization was performed by cyclic voltammetry and galvanostatic charge–discharge measurements. The results show that Co(OH)2−Ni(OH)2/USY microstructure applied for the electrochemical energy storage has displayed superior capacitive performance. The effect of heat treatment conditions on specific capacitance properties was also systemically explored. Upon annealing at 250°C, the maximum specific capacitance was up to 479F/g (or 1,710F/g after correcting for the weight percent of Co(OH)2−Ni(OH)2 phase). Annealing temperatures higher than 250°C may cause the hydroxide to form oxide phase and decrease the surface activity of the oxide, thereby leading to a decline of the specific capacitance.Journal of Solid State Electrochemistry 01/2007; 11(5):571-576. · 2.13 Impact Factor -
Article: Synthesis and electrochemical properties of chemically substituted LiMn2O4 prepared by a solution-based gel method.
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ABSTRACT: Lithium manganese oxide, LiMn(2)O(4), and its substituted samples LiM(0.05)Mn(1.95)O(4) (M=Al, Co, and Zn) were first prepared by a cost-saving and effective new solution-based gel method using a mixture of acetate and ethanol as the chelating agent. The physical properties of the synthesized samples were investigated by thermogravimetry/differential thermal analysis, X-ray diffraction, and scanning electronic microscopy. The as-prepared powders were used as positive materials for a lithium-ion battery, whose charge/discharge properties and cycle performance were examined. The results revealed that all the substituted samples had better cycle performance than pure LiMn(2)O(4). Among these synthesized materials, the LiCo(0.05)Mn(1.95)O(4) sample had the best cycle performance. After 30 cycles, its capacity loss was only 3%. Therefore, cyclic voltammetry and electrochemical impedance spectroscopy were employed to characterize the reactions of Li ion insertion into and extraction from LiCo(0.05)Mn(1.95)O(4) electrodes.Journal of Colloid and Interface Science 09/2006; 300(2):633-9. · 3.07 Impact Factor -
Article: Preparation of hexagonal nanoporous nickel hydroxide film and its application for electrochemical capacitor
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ABSTRACT: Nanoporous nickel hydroxide film has been successfully electrodeposited on titanium substrate from nickel nitrate dissolved in the aqueous domains of the hexagonal lyotropic liquid crystalline phase of Brij 56. Low-angle X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM) studies show that the film has a regular nanostructure consisting of a hexagonal array of cylindrical pores with a repeat center-to-center spacing of about 7 nm. Preliminary electrochemical studies are carried out using cyclic voltammetry (CV) and chronopotentiometry technology. A maximum specific capacitance of 578 F g−1 could be achieved for the nanoporous Ni(OH)2 film electrode, suggesting its potential application in electrochemical capacitors.Electrochemistry Communications. -
Article: Novel porous anatase TiO2 nanorods and their high lithium electroactivity
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ABSTRACT: We demonstrated a simple approach for the synthesis of a kind of novel porous anatase TiO2 nanorods. The method is based on a reaction in composite-hydroxide eutectic system and normal atmosphere without using an organic dispersant or capping agent. The synthesis technique is cost effective, easy to control and is adaptable to mass production. This is the first time TiO2 nanorods with a porous structure are fabricated by using this method. The as-prepared material was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), nitrogen adsorption and desorption experiments and electrochemical measurements. The results showed that the anatase TiO2 nanorods obtained in our experiment have a large specific surface area with a porous structure which makes it have a potential application in catalysts and battery materials, especially in lithium ion batteries. In this study, we mainly tested their electrochemical performance as negative materials for lithium ion batteries. Further research to optimize synthesis conditions, particularly to develop their application in the field of catalysis is currently in progress.Electrochemistry Communications. -
Article: Preparation and electrochemical properties of LiMn2O4 by the microwave-assisted rheological phase method
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ABSTRACT: Pure-phase and well-crystallized spinel LiMn2O4 powders as cathode materials for lithium-ion batteries were successfully synthesized by a new simple microwave-assisted rheological phase method, which was a timesaving and efficient method. The physical properties of the as-synthesized samples compared with the pristine LiMn2O4 obtained from the rheological phase method were investigated by thermogravimetry analysis (TGA), X-ray diffraction (XRD) and scanning electronic microscope (SEM). The as-prepared powders were used as positive materials for lithium-ion battery, whose charge/discharge properties and cycle performance were examined in detail. The powders resulting from the microwave-assisted rheological phase method were pure, spinel structure LiMn2O4 particles of regular shapes with distribution uniformly, and exhibited promising electrochemical properties for battery. Furthermore, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the reactions of Li-ion insertion into and extraction from LiMn2O4 electrode.Electrochimica Acta. -
Article: Enhancement of the electrochemical properties of LiMn2O4 through Al3+ and F− co-substitution
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ABSTRACT: The cathode-active materials LiMn2O4, LiAl0.1Mn1.9O4, and LiAl0.1Mn1.9O3.9F0.1 were synthesized by a microwave-assisted sol–gel method. The influence of different doping elements on the structural and electrochemical properties of the as-prepared samples was investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical experiments. The results indicated that fluorine plays an important role in controlling the morphology, and the doped aluminum could enhance significantly the stability of spinel-type LiMn2O4. The initial discharge capacity of the Al3+ and F− co-substituted specimen reached 129.8 mA h/g and has a high capacity retention after 40 cycles. The outstanding electrochemical properties of LiAl0.1Mn1.9O3.9F0.1 make it a possible promising cathode material for lithium-ion batteries.Graphical abstract The effect of LiF on controlling morphology and particle size, and the material's high specific capacity and good cycleability were discussed.Journal of Colloid and Interface Science 291(2):433-437. · 3.07 Impact Factor -
Article: Carbon nanotube/polyaniline composite as anode material for microbial fuel cells
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ABSTRACT: A carbon nanotube (CNT)/polyaniline (PANI) composite is evaluated as an anode material for high-power microbial fuel cells (MFCs). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) are employed to characterize the chemical composition and morphology of plain PANI and the CNT/PANI composite. The electrocatalytic behaviour of the composite anode is investigated by means of electrochemical impedance spectroscopy (EIS) and discharge experiments. The current generation profile and constant current discharge curves of anodes made from plain PANI, 1 wt.% and 20 wt.% CNT in CNT–PANI composites reveal that the performance of the composite anodes is superior. The 20 wt.% CNT composite anode has the highest electrochemical activity and its maximum power density is 42 mW m−2 with Escherichia coli as the microbial catalyst. In comparison with the reported performance of different anodes used in E. coli-based MFCs, the CNT/PANI composite anode is excellent and is promising for MFC applications.Journal of Power Sources 170(1):79-84. · 4.95 Impact Factor -
Article: Electrochemical properties and synthesis of LiAl0.05Mn1.95O3.95F0.05 by a solution-based gel method for lithium secondary battery
Journal of Solid State Chemistry. 178(3):897-901.
Top co-authors
Top Journals
Institutions
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2007
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Nanyang Technological University
- School of Chemical and Biomedical Engineering
Singapore, Singapore -
Nanjing University of Aeronautics & Astronautics
- Department of Material Science and Technology
Nanjing, Jiangsu Sheng, China
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