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Jingguang G Chen - One of the best experts on this subject based on the ideXlab platform.

  • insight into the synergistic effect between nickel and tungsten carbide for catalyzing urea Electrooxidation in alkaline electrolyte
    Applied Catalysis B-environmental, 2018
    Co-Authors: Lu Wang, Nebojsa Marinkovic, Shyam Kattel, Minhua Shao, Bolun Yang, Jingguang G Chen
    Abstract:

    Abstract Tungsten carbide modified nickel (Ni-WC/C) catalyst is synthesized through the sequential impregnation method and evaluated for the Electrooxidation of urea in alkaline electrolyte. Both the activity and stability of Ni are enhanced by the introduction of WC. In situ Fourier transform infrared (FTIR) measurements combined with electrochemical analysis were used to provide a better understanding of the mechanism for urea Electrooxidation on the Ni-based catalysts. The formation of CO2 and NCO− species is detected during urea oxidation, and the synergistic effect resulting from the interaction of Ni and WC is also proposed. The Ni-WC/C electrode contributes to the improved C–N bond cleavage in urea than that on Ni/C, resulting in a higher activity. Furthermore, the introduction of WC also enhances the anti-poisoning ability, thus promoting more complete oxidation of urea to produce CO2, which leads to a higher energy conversion efficiency than that on Ni/C. This work provides a new strategy for designing highly efficient catalysts for urea Electrooxidation.

  • analyzing the Electrooxidation of ethylene glycol and glucose over platinum modified gold electrocatalysts in alkaline electrolyte using in situ infrared spectroscopy
    Journal of Power Sources, 2016
    Co-Authors: Elizabeth G Mahoney, Wenchao Sheng, Mei Cheng, Jingguang G Chen
    Abstract:

    Abstract Platinum modified gold (Pt/Au) catalysts are evaluated for the Electrooxidation of ethylene glycol (EG) and glucose (Glc). The Pt/Au catalysts are synthesized on an Au disk and supported Au/C particles through the galvanic displacement of a copper monolayer with Pt. The Pt/Au catalysts are compared to monometallic Pt and Au catalysts for the oxidation of EG and Glc in alkaline electrolyte. The Pt/Au disk has an onset potential for these reactions that is similar to Pt and is lower than Au. The supported catalysts are less active toward the Electrooxidation of EG and Glc than the corresponding disk electrodes, but the Pt/Au/C also has an onset potential similar to Pt/C. In-situ FTIR is used to analyze the C–C bond scission in both reactions on the surfaces of Pt, Au, and Pt/Au disks. While the Pt/Au disk is found to have a low onset potential for the oxidation of EG, it does not produce as much CO 2 as bulk Pt. On the other hand, the FTIR results show that CO 2 is produced for the oxidation of Glc on the Pt/Au disk. These results show promise for the possibility of decreasing the amount of Pt needed for the Electrooxidation of polyol molecules.

  • analyzing the Electrooxidation of ethylene glycol and glucose over platinum modified gold electrocatalysts in alkaline electrolyte using in situ infrared spectroscopy
    Journal of Power Sources, 2016
    Co-Authors: Elizabeth G Mahoney, Wenchao Sheng, Mei Cheng, Jingguang G Chen
    Abstract:

    Abstract Platinum modified gold (Pt/Au) catalysts are evaluated for the Electrooxidation of ethylene glycol (EG) and glucose (Glc). The Pt/Au catalysts are synthesized on an Au disk and supported Au/C particles through the galvanic displacement of a copper monolayer with Pt. The Pt/Au catalysts are compared to monometallic Pt and Au catalysts for the oxidation of EG and Glc in alkaline electrolyte. The Pt/Au disk has an onset potential for these reactions that is similar to Pt and is lower than Au. The supported catalysts are less active toward the Electrooxidation of EG and Glc than the corresponding disk electrodes, but the Pt/Au/C also has an onset potential similar to Pt/C. In-situ FTIR is used to analyze the C–C bond scission in both reactions on the surfaces of Pt, Au, and Pt/Au disks. While the Pt/Au disk is found to have a low onset potential for the oxidation of EG, it does not produce as much CO 2 as bulk Pt. On the other hand, the FTIR results show that CO 2 is produced for the oxidation of Glc on the Pt/Au disk. These results show promise for the possibility of decreasing the amount of Pt needed for the Electrooxidation of polyol molecules.

C Lamy - One of the best experts on this subject based on the ideXlab platform.

J K Astik - One of the best experts on this subject based on the ideXlab platform.

  • kinetics of Electrooxidation of landfill leachate in a three dimensional carbon bed electrochemical reactor
    Chemosphere, 2009
    Co-Authors: Misra Rohit, Gedam Nitin, P N Parameswaran, J K Astik
    Abstract:

    Abstract The Electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the kinetics and mechanism of Electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1–3 A) for a period of 6 h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60–64% COD was removed within 1 h with a rate constant 5.83 × 10 −3 min −1 in Phase I, which was near 5–7 times greater than that of Phase II (0.81–1.03 × 10 −3  min −1 ). The mineralization efficiency was found to be significant in the range 0.83–0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of Electrooxidation was discussed with the help of adsorption, kinetic and SEM results.

  • kinetics of Electrooxidation of landfill leachate in a three dimensional carbon bed electrochemical reactor
    Chemosphere, 2009
    Co-Authors: Misra Rohit, Gedam Nitin, P N Parameswaran, J K Astik
    Abstract:

    Abstract The Electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the kinetics and mechanism of Electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1–3 A) for a period of 6 h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60–64% COD was removed within 1 h with a rate constant 5.83 × 10 −3 min −1 in Phase I, which was near 5–7 times greater than that of Phase II (0.81–1.03 × 10 −3  min −1 ). The mineralization efficiency was found to be significant in the range 0.83–0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of Electrooxidation was discussed with the help of adsorption, kinetic and SEM results.

J.-m. Léger - One of the best experts on this subject based on the ideXlab platform.

Jean-michel Léger - One of the best experts on this subject based on the ideXlab platform.

  • Dimethoxymethane (DMM) Electrooxidation on polycrystalline platinum electrode in acid media
    Journal of electroanalytical chemistry and interfacial electrochemistry, 2008
    Co-Authors: G. Kéranguéven, Françoise Hahn, Eric Sibert, Jean-michel Léger
    Abstract:

    The Electrooxidation of dimethoxymethane (DMM) was studied on polycrystalline platinum electrode. Cyclic voltammetry has shown that the behaviour of DMM Electrooxidation depends on scan rate, DMM concentration and the nature of anion of the supporting electrolyte. At a low scan rate or at a high DMM concentration, the electrode is strongly poisoned during DMM Electrooxidation, which is an anion-sensitive reaction. Using electrochemical and in situ IR experiments, a multistep mechanism was proposed with DMM adsorption as the first and rate-determining step. At a low potential range, adsorbed CO is slowly formed. COads inhibits the DMM Electrooxidation until it is full oxidized to CO2. Conversely, for lower adsorbed CO coverage, oxidation starts earlier and CO2 formation is observed. In situ infrared reflectance spectroscopy experiments were carried out to identify these adsorbed species intermediates and reaction products of DMM adsorption and oxidation. In addition to adsorbed COL (linearly bonded CO), adsorbed HCO, CH3O species and CO2 were detected suggesting a complex mechanism of the Electrooxidation of DMM, with parallel paths involving methanol and formaldehyde Electrooxidation.

  • ethylene glycol Electrooxidation in alkaline medium at multi metallic pt based catalysts
    Journal of Electroanalytical Chemistry, 2007
    Co-Authors: Laurent Demarconnay, Christophe Coutanceau, Sylvain Brimaud, Jean-michel Léger
    Abstract:

    Abstract The Electrooxidation of ethylene glycol at nanostructured platinum based catalysts was studied in alkaline medium. The optimum metals loading and atomic composition for ethylene glycol Electrooxidation were determined. The addition of Bi to platinum leads to decrease the onset potential of EG Electrooxidation of about 70 mV and to achieve higher current densities in the whole studied potential range. The ternary catalyst PtPdBi/C does not change the onset potential of EG oxidation, but leads to increase the current densities compared to PtBi catalysts. The EG Electrooxidation enhancement with binary and ternary catalysts was confirmed in SAMFC (solid alkaline membrane fuel cell) experiments, the open circuit voltage (ocv) increasing from 0.66 to 0.83 and 0.81 V and the maximum achieved power density raising from 19 to 22 and 28 mW cm −2 with Pt, PtBi and PtPdBi catalysts, respectively. An attempt to explain the change in catalytic behavior was made by analysis of SAMFC reaction products in the anode outlet and by in situ FTIR spectroscopy measurements. It was shown that the addition of foreign atoms to platinum led to decrease the ability of the catalyst to break the C–C bond, likely due to dilution of surface platinum atoms. But, in the same time, catalyst containing Pd and Bi seems to activate the oxidation of EG in oxalate compared to pure platinum. The role of Bi and Pd was discussed. It was proposed that Bi mainly favors the adsorption of OH species but also affects the product distribution by changing the composition of chemisorbed species, whereas Pd only limits the poisoning of Pt sites by changing the composition of chemisorbed species.

  • How bimetallic electrocatalysts does work for reactions involved in fuel cells?: Example of ethanol oxidation and comparison to methanol
    Electrochimica Acta, 2005
    Co-Authors: Jean-michel Léger, Françoise Hahn, Christophe Coutanceau, Séverine Rousseau, Claude Lamy
    Abstract:

    Carbon-supported Pt-based nanosized electrocatalysts can be synthesized for methanol and ethanol Electrooxidation. The electrocatalytic activity of Pt can be greatly enhanced by using Pt-Ru/C for methanol oxidation or Pt-Sn/C for ethanol oxidation. In situ IR reflectance spectroscopy is a convenient tool to better understand the importance of the different adsorption steps involved in the mechanisms of Electrooxidation. With Pt/C, it appears clearly that linearly adsorbed CO is the poisoning species formed during methanol and ethanol oxidation. In the case of methanol, even with Pt-Ru/C (the most active catalyst), adsorbed CO is also a reactive intermediate. The enhancement of activity observed in such a case is due to the possibility to activate water at lower potentials in the presence of Ru. With Pt-Sn/C, the mechanism of the Electrooxidation of ethanol is strongly modified. If at low potentials, poisoning with adsorbed CO still exists (as with Pt/C), the oxidation of ethanol at potentials greater than 0.4 V versus RHE occurs through an adsorbed acetyl species which can lead to the formation of acetaldehyde and acetic acid as final products in addition to carbon dioxide.