Papers by Keyword: Direct Ethanol Fuel Cell (DEFC)

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Authors: Long Long Wang, Qiao Xia Li, Tian Yu Zhan, Qun Jie Xu
Abstract: Direct ethanol fuel cells are considered a promising power source for future portable electronic and automotive applications. This article reviewed the synthetic methods commonly used to prepare Pd-based catalysts for the ethanol electrooxidation in alkaline media. The progress in the mechanism studies of ethanol oxidation reaction (EOR) on Pd electrode in alkaline medium by cyclic voltammetry and electrochemical in situ FTIR spectroscopy was also reviewed. The recent studies revealed that the EOR is fairly complicated, and it is difficult in CC bond cleavage for the complete oxidation of ethanol to CO2, and ethanol is selectively oxidized to acetate on Pd-based catalysts in alkaline media. Overall, what is most important is to explore new Pd-based alloy catalysts with high ability to break the CC bond to promote complete oxidation of ethanol as well as increase the efficiency of DEFCs.
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Authors: Nobuyoshi Nakagawa, Takashi Watanabe, Masatsugu Wagatsuma, Takuya Tsujiguchi
Abstract: Carbon-supported PtRuRh nanoparticles, PtRuRh/C, were prepared by an impregnation method as a new anode catalyst with a high activity for ethanol oxidation in a direct ethanol fuel cell (DEFC). PtRuRh (2:1:1)/C, of which the metal loading and the metal particle diameter was 40 wt% and 6.7 nm, respectively, with the metal composition of 2:1:1 for Pt:Ru:Rh, showed a higher oxidation current at a certain electrode potential compared to that of PtRu (1:1)/C and Pt/C prepared in a similar manner. The DEFC with PtRuRh (2:1:1)/C as the anode catalyst generated about a 1.5 times and 3 times higher electric power compared to that of PtRu (1:1)/C and Pt/C, respectively, with 2M ethanol.
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Authors: Zhong Xu Dai, Dan Ni Tian, Xin Zhang, Si Lin Gong, Chang Ying Yang
Abstract: To investigate the influence of ethanol catalyzed oxidation on activity of Pd/C with different ratio of Pd and C. Pd/C catalyst samples with Pd loads of 20, 30, 40 and 50 wt% were obtained by chemical reduction reaction of PdCl2 and NaBH4. The samples morphology and structure were characterized by XRD and SEM. The electrocatalytic oxidation activities of ethanol were examined by cyclic voltammetry in alkaline media. The results show that a face centered cubic (FCC) Pd phase can be identified in the sample powders. The average particle size of the Pd/C powder is about 10 nm. The performance of ethanol oxidation on 40 % Pd/C electro-catalyst is better than that of the other Pd/C samples.
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Authors: Sawanya Kanjanapaisit, Chaiwat Prapainainar, Paweena Prapainainar
Abstract: Composite membranes, consist of Nafion and surface-modified mordenite as inorganic filler functioned as ethanol barrier, were prepared and used for direct ethanol fuel cell (DEFC). mordenite was modified using gamma-glycidoxypropyltrimethoxysilane (GMPTS) which has the epoxide group and 3-mercaptopropyl-trimethoxysilane (MPTS) which has the mercapto group as coupling agents on mordenite. The composite membranes were fabricated by adding 5 %weight modified mordenite into Nafion by solution casting and hot pressing with catalyst to produce MEA and tested in DEFC single cell stack. XRD, FT-IR, Mastersizer and SEM were used to study the morphology, physical and chemical properties of the filler and the composite membrane. The characterizations also included ethanol permeability and proton conductivity by using the diffusion cell and AC impedance test, respectively. The performance of the cell was evaluated in the DEFC under cell temperature from 30 to 70 °C and ethanol concentration of 1 M to 4 M. It was then compared to the recasted Nafion membrane.
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Authors: Dong Tang, Wen Shuai Zhao
Abstract: The sintered body of tubular cathode for Direct Ethanol Fuel Cell (DEFC) is prepared by the gelcasting process using a certain proportion of graphite powder and mesocarbon microbead (MCMB). The electrical performance under different air flow rates, operating temperature, porosity of cathode diffusion layer, inlet pressure and different thickness of catalyst layer are analyzed by the combination of experimental and numerical simulation method. The results show that the increase of diffusion layer porosity, inlet pressure, thickness of catalyst layer and operating temperature are benefit for the improvement of the cell performance. Moreover, the electrical performance is improved when the air flow rate is 100 mL/min.
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Authors: Yang Zhang, Dong Tang, Rui Xue Duan, Hong Jun Ni
Abstract: A new tubular cathode support for Direct Ethanol Fuel Cell (DEFC) was prepared by the gelcasting process using mesocarbon microbead(MCMB) and graphite as the main raw materials. The effects of different graphite doping ratios on tensile strength, bending strength, crushing strength, volume resistivity and shrinkage rate for the prepared tubular cathode support were studied by experimental test. The result showed that the prepared tubular cathode support had very good comprehensive performance. The tubular cathode support with 10% graphite exhibits the best performance such as bending strength 25MPa and resistivity30µΩ•m, and it satisfied the DEFC cathode working conditions and performance requirements.
2345
Authors: Hong Jun Ni, Can Can Lv, Cheng Jin Zhang, Ping Liao
Abstract: Membranes are made by doping and modifying the Nafion117 with Nano-silica(SiO2). The penetration and the proton conductivity of composite membrane are studied through gas chromatograph and electrochemical workstation. With the help of cross-section spectrum, it shows that the SiO2 particles can penetrate the internal membrane and the weight percentage is greater than 0.1% after doping and modifying the membranes of Nafion117, so the SiO2 particles has a very good combination with the substrate. The membrane which is handled by Sol on 60°C has high proton conductivity and high water retention performance in high temperature. The permeability coefficient of membrane which is handled by Sol on 60°C and by the other ways are 4.07×10-4cm2/s and 8.13×10-4 cm2/s respectively. It shows that the permeability coefficient of ethanol membrane is reduced by half after the Nafion117 membrane is handled by Sol on 60°C.
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Authors: Koichi Niwa, Toshiaki Tanaka, Yasuro Ikuma
Abstract: The process of obtaining a uniform dispersion of nanosized powders by applying two step process of mixing and adjusting viscosity was studied. The mixed paste was used as the electrode of direct ethanol fuel cells (DEFC). And power density of the fuel cells was measured. A high power density was realized by addition of acetone and propanol solvents to nanosized silica powder. However acetaldehyde concentration during the operation of these fuel cells did not decrease. An excess methanol was added to membrane electrode assembly composition of DEFC. The power density and current of DEFC were improved by adding methanol solvent. However, methanol addition over 55 % did not improve dispersion of nanosized powders. Transmission electron microscopy observation suggests that over 55% of methanol addition does not give good dispersion of nanosized powders.
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Authors: Hong Jun Ni, Can Can Lv, Xu Hong Wang, Yu Zhu, Ming Yu Huang
Abstract: A carbon supported Pt-SnO2/C catalyst was prepared by hydrothermal method .The Pt-SnO2/C electrode was prepared by electrostatic spinning. Factors of product in solution, different Nafion loading and different loading of Pt-SnO2/C catalyst were evaluated for their effects on ethanol oxidation reaction (EOR). Electrocatalyst was characterized by SEM,EDS and XRD. At the same time, Electrocatalyst was tested by cyclic voltammetry (CV) , Chronoamperometry, AC impedance at three-electrode under similar conditions to those of the DEFC. The results show that the Nafion loadings was 7.5wt.%, which the loading amount of Pt was 1.5mg•cm-2, the Pt-SnO2/C electrode has the highest activity for ethanol oxidation. Compared to the low potential, the oxidation peak current density was 2 times high obtained.
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Authors: Bai Yang Lou, Han Zhou, Bin Xu
Abstract: The modification of Nano Pt and carbon black compound coating on the fuel cell’s graphite electrode by the method of vacuum ion plating and ethanol catalytic combustion. The microstructures and the electro catalysis properties of the electrode surface before and after the modification were analyzed and tested with the methods of scanning electron microscope(SEM), transmission electron microscope(TEM), electrochemical workstation and so on. The effects of nano Pt and carbon black on the electrode’s electro catalysis properties were investigated. The Study results have shown that carrying on electrochemical properties test to the graphite electrode which has been treated with nano Pt and carbon black compound surface modification, there will be three oxidation peaks in its cyclic voltammograms and the background current will be higher. Compared with the nano Pt surface modification, the electrode which has been treated with nano Pt and carbon black compound surface modification has better ethanol electro catalysis properties. The high specific surface area acquired from the nano carbon black surface modification and the synergic action of the catalytic material Pt can improve the ethanol electro catalysis properties of the electrode effectively.
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