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2002

Chinese Chemical Society | Xiamen University

Chemical Engineering

Articles 1 - 21 of 21

Full-Text Articles in Chemistry

Mechanistic Study Of Oxidation Of Hypophosphite On Pt Electrodes By Sniftirs, Tai-Xiang Jiang, Hui-Huang Wu Nov 2002

Mechanistic Study Of Oxidation Of Hypophosphite On Pt Electrodes By Sniftirs, Tai-Xiang Jiang, Hui-Huang Wu

Journal of Electrochemistry

The oxidation of hypophosphite on a polycrystalline platinum electrode was studied by SNIFTIRS and cyclic voltammetry, the in-situ IR spectra were analyzed as a function of Pt electrode potentials in the solution of 0.5 mol/L H 2SO 4+0.1 mol/L NaH 2PO 2. It was found that the dissociative adsorption of hypophosphite ions occurs on Pt surface, and the oxidation product is H 3PO 4, rather than H 2PO 3 - which was considered to produce on Ni electrodes, thereby a new insight into mechanism of hypophosphite oxidation on Pt in acidic media was provided.

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Nano-Sized Cobalt-Based Oxides As Negative Electrode For Lithium-Ion Batteries, Feng Huang, Zheng-Yong Yuan, Yun-Hong Zhou, Ju-Tang Sun Nov 2002

Nano-Sized Cobalt-Based Oxides As Negative Electrode For Lithium-Ion Batteries, Feng Huang, Zheng-Yong Yuan, Yun-Hong Zhou, Ju-Tang Sun

Journal of Electrochemistry

Nanosized cobalt-based oxide (Co 3O 4, CoB 1.36 O 2.8 and CoB 0.5 Al 0.1 O 1.5 ) samples were prepared by rheological phase method and were tested as anodes in secondary lithium batteries. The cells were cycled between 0.01V and 3.00 V. The best electrochemical performance was obtained from the Li/Co 3O 4 cell, which retained 95% of its initial capacity (931 mAh/g) after 30 cycles. The doping of B, Al reduced the reversible capacity during the first discharge/charge cycle, and the quantity of reversible capacity reduced with B, A1 increasing. The modifying structures at difference charge and discharge …

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Electrocatalytic Oxidation Of Formic Acid On Molybdate-Modified Platinum Electrode, Jun-Hua Du, Xue-Hui Xu, Hong Li, Hong-Yu Cheng, Wei-Shan Li Nov 2002

Electrocatalytic Oxidation Of Formic Acid On Molybdate-Modified Platinum Electrode, Jun-Hua Du, Xue-Hui Xu, Hong Li, Hong-Yu Cheng, Wei-Shan Li

Journal of Electrochemistry

The electrochemical behavior of molybdates on a platinum electrode in H 2SO 4 solutions with different H 2SO 4 concentrations was studied by cyclic voltammetry and double chronoamperometry. Molybdates were reduced to adsorb hydrogen molybdenum bronzes on the platinum electrode in H 2SO 4 solutions during cathodically potential sweep. The hydrogen molybdenum bronzes were oxidized to different forms of hydrogen molybdenum bronzes with less hydrogen, depending on the H 2SO 4 concentration. Platinum electrode was modified by these hydrogen molybdenum bronzes. However, this modified electrode was not stable in H 2SO 4 solutions. The modified electrode was used to study …

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Preparation And Performance Of Lifeo_2 Coated Nickel Oxide Cathode For Molten Carbonate Fuel Cells, Chun-Ming Wang, Fei Li, Ke-Ao Hu Nov 2002

Preparation And Performance Of Lifeo_2 Coated Nickel Oxide Cathode For Molten Carbonate Fuel Cells, Chun-Ming Wang, Fei Li, Ke-Ao Hu

Journal of Electrochemistry

A novel cathode for molten carbonate fuel cells was prepared by coating LiFeO 2 over the surface of porous NiO cathode by a simple combustion process. The analytical results of X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the LiFeO 2 coating on the surface of NiO particles consisted of nonometer-sized LiFeO 2 grains and sintered tightly with the NiO particles. The LiFeO 2 coating dramatically reduced the contacting area of NiO with the carbonate melts, thus the solubility of NiO in the carbonate melts was decreased. Meanwhile, …

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Review Of Mathematical Model For Proton Exchange Membrane Fuel Cell, Shan-Hai Ge, Bao-Lian Yi, Hua-Min Zhang Nov 2002

Review Of Mathematical Model For Proton Exchange Membrane Fuel Cell, Shan-Hai Ge, Bao-Lian Yi, Hua-Min Zhang

Journal of Electrochemistry

In the review with 49 references, the mathematical models for proton exchange membrane fuel cell (PEMFC) were summarized. The mechanistic model and empirical model were introduced. Transfer in the membrane, catalyst layer,diffusion layer and flow field of PEMFC were described. The importance of water and heat management was analyzed. The dimension, complexity and solving methods of the PEMFC model were discussed. The importance and validity to develop a model with time dimension are put forward.

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Manufacture Of 1 Kw Molten Carbonate Fuel Cell Stack, Sheng Sui, Xin-Jian Zhu, Zheng-Yu Fan, Cao Guang-Yi And Nov 2002

Manufacture Of 1 Kw Molten Carbonate Fuel Cell Stack, Sheng Sui, Xin-Jian Zhu, Zheng-Yu Fan, Cao Guang-Yi And

Journal of Electrochemistry

A molten carbonate fuel cell stack with an active area of 240 mm×140 mm consisted of 30 cells.The gas feed system works via interior manifolds,and the stack placed in a couple of self-chest,coupled with a heater at the bottom and other fours surrounded,to keep uniformity of temperature.Under ambient pressure and 650 ℃,fed with hydrogen and air as anode and cathode gases respectively,the stack gave a current density of 150 mA/cm 2 at an average cell voltage of 0.7 V.The peak output of the stack was 1.06 kW during its performance of 300 h.

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Steady State Simulation Of Ysz Intermediate-Temperature Fuel Cell, Zi-Jing Lin, Ye Gu, Xiao-Hua Zhang Nov 2002

Steady State Simulation Of Ysz Intermediate-Temperature Fuel Cell, Zi-Jing Lin, Ye Gu, Xiao-Hua Zhang

Journal of Electrochemistry

With a coupled 2D electrochemical and thermal modeling software, the characteristics of the steady state operation of the intermediate-temperature fuel cell with thin yttria-stabilized zirconia(YSZ) electrolyte was analyzed. The parameters of I-V equation were obtained from fitting the experiment results and the choice of grid points was determined by balancing the accuracy requirement and computational efficiency. The temperature fields at different operation circumstances such as flow designs, material choices for interconnect, were examined. The dependences of the output power and cell efficiency on the operating voltage at different temperatures were studied. Based upon the analysis of the temperature profile, it …

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Synthesis And Characterization Of Lini_(0.8-X)Al_Xco_(0.2)O_2 As Cathodes For Lithium-Ion Batteries, Jun Zhang, Zhong-Kao Jin, Qing-He Yang, Qing-Mei Song, Xiao-Hua Ma, Xiang-Fu Zong Aug 2002

Synthesis And Characterization Of Lini_(0.8-X)Al_Xco_(0.2)O_2 As Cathodes For Lithium-Ion Batteries, Jun Zhang, Zhong-Kao Jin, Qing-He Yang, Qing-Mei Song, Xiao-Hua Ma, Xiang-Fu Zong

Journal of Electrochemistry

Single_phase solid solution of LiNi 0.8- x Al x Co 0.2 O 2 (0≤ x <0.1)had been synthesized and characterized by X_ray diffraction(XRD) and scanning electron microscopy (SEM). Their electrochemical performance was examined by charge_discharge cycling.The LiNi 0.71 Al 0.09 Co 0.2 O 2 compound showed a discharge capacity of 152 mAh/g after 20 cycles that corresponds to 97.4% capacity retention. The beneficial effect of co_doping with Al and Co elements was corro_borated by slow scanning cyclic voltammograms(SSCV),electrochemical impedance spectrum(EIS)and differential scanning calorimetry(DSC) data on charged cathodes. These results show that the 2D_character of the crystal lattice was stabilized by co_doping with Al and Co, the phase transitions that occur during deintercalation or intercalation of Li_ions were significantly suppressed,and thermal stability in the charged state was also improved.

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Ionic Conduction In Ba_(0.95)Ce_(0.9)Y_(0.1)O_(3-Α)Solid Oxide And Its Performance In Fuel Cell, Gui-Lin Ma, Ding-Xian Jia, Li-Gan Qiu, Hui Shi, Rong Chen Aug 2002

Ionic Conduction In Ba_(0.95)Ce_(0.9)Y_(0.1)O_(3-Α)Solid Oxide And Its Performance In Fuel Cell, Gui-Lin Ma, Ding-Xian Jia, Li-Gan Qiu, Hui Shi, Rong Chen

Journal of Electrochemistry

Using Ba 0.95 Ce 0.9 Y 0.1 O 3-α as a solid electrolyte and porous platinum as electrodes,hydrogen and oxygen concentration cells and hydrogen_air fuel cell were constructed,respectively.Electromotive forces(MEFs)of the gas concentration cells and I_V characteristics of the fuel cell were detdrmined in the temperature range of 600～1 000 ℃.The Ba 0.95 Ce 0.9 Y 0.1 O 3-α exhibited almost the pure protonic conduction under hydrogen gas,and a mixed conduction of oxide_ion and electron hole with oxide_ion transport number of 0.3～0.5 under oxygen gas.It exhibited a mixed conduction of proton and oxide_ion with the total ion transport number above 0.9 …

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Optimum Of Catalyst Layers For Direct Methanol Fuel Cells, Jun Zhang, Lei Li, Li Xu, Yu-Xin Wan Aug 2002

Optimum Of Catalyst Layers For Direct Methanol Fuel Cells, Jun Zhang, Lei Li, Li Xu, Yu-Xin Wan

Journal of Electrochemistry

The performances of membrane electrode assemblies (MEAs)with various Pt loading were compared.The amount of Nafion in a catalytic layer was optimized,and the effect of Nafion loading on the resistance of MEAs was investigated with ac impedance spectroscopy.For a MEA with both Pt 4 mg/cm 2 in the anode and the cathode,suitable Nafion loading was 21.4 wt% in the anode.With 21.4 wt% Nafion loading in the cathode,the Direct Methanol Fuel Cells(DMFC) showed the highest performance at high current density.While,the DMFC performances came down,as Nafion loading increasing,for ohm and concentration polarization.

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Syntheses And Photoluminescence Of Zinc Oxide Polyaniline Coaxial Nanowires And Their Array, Zhi-Xin Zheng, Yan-Yan Xi, Ping Dong, Huai-Guo Huang, Jian-Zhang Zhou, Lin-Lin Wu, Zhong-Hua Lin May 2002

Syntheses And Photoluminescence Of Zinc Oxide Polyaniline Coaxial Nanowires And Their Array, Zhi-Xin Zheng, Yan-Yan Xi, Ping Dong, Huai-Guo Huang, Jian-Zhang Zhou, Lin-Lin Wu, Zhong-Hua Lin

Journal of Electrochemistry

A novel nanomaterial,zinc oxide (ZnO) and polyaniline (PANI) coaxial nanowires and their array in the template,was synthesized using anodic aluminum oxide (AAO) membrane as template.The morphology of these coaxial nanowires was observed with transmission electron microscope (TEM).The experiments on photoluminescence (PL) of coaxial nanowires and their array in AAO membrane show that the visible emission band of ZnO shifts from 530 nm to 400 nm and the luminescence is enhanced for the coaxial nanowires array in AAO membrane,and the visible emission band shifts to a lower wavelergth(385 nm) for coatial nanowires in NaOH solution. Possible explanations for these two blue …

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Preparation,Structure And Properties Of Electrochromic Rhodium Oxide Films, Hai-Hong Wang, Tao Wang, Man-Ming Yan, Zhi-Yu Jiang May 2002

Preparation,Structure And Properties Of Electrochromic Rhodium Oxide Films, Hai-Hong Wang, Tao Wang, Man-Ming Yan, Zhi-Yu Jiang

Journal of Electrochemistry

Electrochromic rhodium oxide films were prepared on ITO substrate by sol_gel method. The films exhibited reversible two_color (bright yellow at reduction and dark green at oxidation) electrochromic behavior in alkaline solution with good cycle stability. In_situ XRD, TGA_DTA, IR, XPS methods were used for studying the structure and chemical process of the films. The diffusion coefficient during the electrochromic process was measured by electrochemical impedance spectra method. It was found that the rhodium oxide films may be suitable for the use in electrochromic devices.

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A Blend Conducting Membranes For Direct Methanol Fuel Cells, Lei Li, Jun Zhang, Hong Wu, Yu-Xin Wang May 2002

A Blend Conducting Membranes For Direct Methanol Fuel Cells, Lei Li, Jun Zhang, Hong Wu, Yu-Xin Wang

Journal of Electrochemistry

An attempt was made to modify membranes for direct methanol fuel cells by blending Nafion or polystyrene sulfonic acid (PSSA) with polyvinylidene fluoride (PVDF) from their solutions. The proton conductivity and methanol barrier property as a function of the membrane compositions are discussed. Compared with the Nafion  117 membrane, the PVDF_Nafion blend membranes with 25 wt% of Nafion showed a decrease in the conductivity by about 2 orders of magnitude, and the methanol barrier properties increased about 3 orders of magnitude. If the ratio (σ/P) is adopted to characterize the performance of the membrane, the PVDF_PSSA and PVDF_Nafiion blend …

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Electrochemical Properties Of Mixed Metal Oxide Coated Titanium Anodes In Seawater, Ting-Yong Wang, Li-Kun Xu, Guang-Zhang Chen May 2002

Electrochemical Properties Of Mixed Metal Oxide Coated Titanium Anodes In Seawater, Ting-Yong Wang, Li-Kun Xu, Guang-Zhang Chen

Journal of Electrochemistry

Mixed metal oxide coated titanium anodes prepared by thermal decomposition were characterized by scanning electron microscopy and electrochemical measurement, while the consumption rate of an anode was also measured in seawater. In order to examine the practical performances of mixed metal oxide_coated anodes, a simulating test on floating dock in seawater has also been carried out. The SEM results indicate that oxide layers exhibited a cracked_mud morphology which endows the anode with good electrocatalytic activity. The electrochemical measurements showed that mixed metal oxide_coated anodes exhibit excellent electrochemical activity and electrochemical stability in seawater. Owing to good corrosion resistance and low …

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Electrocatalytic Oxidation Of Formaldehyde On The Proline Film Modified Electrode, Yu-Rong Ma, Qiu-Xia Yang, Guo-Bao Li, Zheng-Kai Xi, Xue-Lin Wang May 2002

Electrocatalytic Oxidation Of Formaldehyde On The Proline Film Modified Electrode, Yu-Rong Ma, Qiu-Xia Yang, Guo-Bao Li, Zheng-Kai Xi, Xue-Lin Wang

Journal of Electrochemistry

The proline film modified electrode and its electrochemical behavior was studied by cyclic voltammetry and spectroelectrochemistry . After incorporation of Ni(Ⅱ), the cyclic voltammograms of the proline Ni(Ⅱ) film electrode exhibited a typical redox peak, which appeared at potential of 0.52 V anodic and 0.44 V cathodic in NaOH. The formal potentials E ' were linearly dependent on the pH, and the peak currents ip were linearly dependent on the square root of the scan rates,thus charge transfer in the film was controlled by diffusion. The diffusion coefficient is figured out to be 2×10 -10 cm 2·s -1 . The …

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Development Of 200～500 W Portable Proton Exchange Membrane Fuel Cell Power System, Li-Qing Hu, Li-Rong Zhou, Zheng Li, Jian-Wei Xia, Ming-Zhu Fu, Xin Wu, Yun Zhu May 2002

Development Of 200～500 W Portable Proton Exchange Membrane Fuel Cell Power System, Li-Qing Hu, Li-Rong Zhou, Zheng Li, Jian-Wei Xia, Ming-Zhu Fu, Xin Wu, Yun Zhu

Journal of Electrochemistry

The Properties of the Portable PEM Fuel Cell Power Source are very unique compared with the common primary or rechargeable electro_chemical battery. This paper describes the In this work, of the 200～500 W portable PEM fuel cell power system, was developed. The system mainly composed of four subsystem:1)Fuel cell stack;2)Air delivery;3)Hydrogen source;4)Heat dissipation and system control.

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Electrosynthesis Of Glyoxylic Acid In A Cooled Cathode Reactor, Jin-Hong Fan, Jun Li, Xue-Yun Chen, Wei Li, Hao-Qi Gao May 2002

Electrosynthesis Of Glyoxylic Acid In A Cooled Cathode Reactor, Jin-Hong Fan, Jun Li, Xue-Yun Chen, Wei Li, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a well designed cooled cathode reactor. The cathodic and anodic electrolytes were super_saturated oxalic acid and hydrochloric acid aqueous solutions separated by a super_acid ion_exchange membrane. The current efficiency and time_space yield of glyoxylic acid were studied under different temperatures of cathode and electrolyte,current densities,materials of cathode. With the cooled cathode reactor, the energy consumption was reduced and higher oxalic acid concentration was available in solution, so that current efficiency was improved. The results indicated that the average time_space yield of glyoxylic acid was about 0.032 kg·dm -3 ·h -1 …

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Electrosynthesis Of Glyoxylic Acid In A Packed Bed Reactor, Jin-Hong Fan, Jun Li, Yu-Zhong Su, Hao-Qi Gao Feb 2002

Electrosynthesis Of Glyoxylic Acid In A Packed Bed Reactor, Jin-Hong Fan, Jun Li, Yu-Zhong Su, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a packed bed reator.The cathodic and anodic electrolytes were super_saturated oxalic and hydrochloric acid aqueous solutions separated by a super_acid ion_exchange membrane.The current efficiency and yield of glyoxylic acid were studied under different structured packed bed reactors and different electrode materials,temperatures and current densities.The results indicated that the current efficiency of synthsis of glyoxylic acid was over 66.2% and the concentration of glyoxylic acid could reach 2.02% after 45min electrolysis with cathode of lead particles and anode of graphite board under conditions of temperature 32 ℃,superficial flow rate of 0.505 …

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Preliminary Study On Direct Ethanol Fuel Cell, Shu-Qin Song, Li-Kang Chen, Jian-Guo Liu, Zhao-Bin Wei, Qin Xin Feb 2002

Preliminary Study On Direct Ethanol Fuel Cell, Shu-Qin Song, Li-Kang Chen, Jian-Guo Liu, Zhao-Bin Wei, Qin Xin

Journal of Electrochemistry

The performance of a direct ethanol fuel cell based on Nafion115 was reported.PtRu/C and Pt/C were used as ethanol anode and oxygen cathode catalysts in a single cell of size 9 cm 2 .The effects of temperature,oxygen pressure,the flow rate of ethanol, and oxygen, and ethanol concentration were tentatively studied.The experimental results showed that the cell open circuit voltage 0.608 V,the cell voltage 0.329 V at 50 mA/cm 2 ,and the peak power density 19.25 mW/cm 2 were reached under the conditions of T cell =85 ℃, P O2 =0.5 MPa, C ethanol =1.0 mol/L and with the flow rate …

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Varying Current Electro-Synthesis Of Glyoxalic Acid In Pairs In The Fixed-Bed Electrolytic Cell, Yin Sheng Chen, Xin Sheng Zhang, Ying Chun Dai, Wei Kang Yuan Feb 2002

Varying Current Electro-Synthesis Of Glyoxalic Acid In Pairs In The Fixed-Bed Electrolytic Cell, Yin Sheng Chen, Xin Sheng Zhang, Ying Chun Dai, Wei Kang Yuan

Journal of Electrochemistry

As for the process of the electro oxidation of glyoxal to glyoxalic acid, the electrolytic result of either fixed bed electrolytic cell or varying current electrolysis was better than that of either flat plate electrolytic cell or constant current electrolysis. The average current density of varying current electro synthesis of glyoxalic acid in pairs was 1535 A/m 2 and the current efficiency were 85.3% and 86.7% and the selectivity were 93.9% and 94.0% for the anodic oxidation and cathodal reduction respectively. The initial composition of anodic electrolyte was 7% glyoxal and 8% hydrochloric acid (W/W) and the cathodal electrolyte consisted …

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Electrochemical Synthesis And Characterization Of The Nickel Electropolyurushiol Coordination Polymer, Feng Gao, Guo-Cai Shen, Jie-Yuan Tang, Wen-Gong Zhang Feb 2002

Electrochemical Synthesis And Characterization Of The Nickel Electropolyurushiol Coordination Polymer, Feng Gao, Guo-Cai Shen, Jie-Yuan Tang, Wen-Gong Zhang

Journal of Electrochemistry

The nickel electropolyurushiol coordination polymer(EPU Ni 2+ ) was obtained by the reaction between nickel chloride isopropyl alcohol solution with electropolyurushiol (EPU).The electrochemical polymerization of urushiol and the preparation of nickel electropolyurushiol coordination polymer were investigated.The coordination polymer was characterized by XPS,FT_IR,DMTA and AES methods,and its composition and structure were determined.The content of Ni 2+ reached up to 7.5%. It was shown that there was certain coordination between Ni 2+ and electropolyurushiol in the coordination polymer,thus cross_links were formed.Therefore the glass transition temperature of the coordination polymer increased and heat resistance was enhanced considerably.

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