Papers by Keyword: Electrocatalyst

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Authors: Jian Min Zhang, Wei Hua Chen
Abstract: A new composite electrocatalyst, well-dispersed TiO2/active carbon (AC), has been assessed with regard to its applicability for oxygen reduction in air electrodes. TiO2/AC powders were prepared by one-step vapor hydrolysis of TiCl4 with active carbon. The structure and composition of the powders were analyzed by means of XRD and FTIR, and the results showed that anatase titanium dioxide of particle size 16.5 nm was produced after calcination at 400 °C. The influences of the preparative parameters of the air electrode on its discharge performance were studied by polarization curve measurements. The terminal voltage of the air battery was maintained at above 1.05 V while the current density of the air electrodes reached 150 mA cm-2. These results show that the composite catalyst has high electrochemical activity for the oxygen reduction reaction.
Authors: T. Maiyalagan, Sivakumar Pasupathi
Abstract: Fuel cells, as devices for direct conversion of the chemical energy of a fuel into electricity by electrochemical reactions, are among the key enabling technologies for the transition to a hydrogen-based economy. Among the various types of fuel cells, polymer electrolyte membrane fuel cells (PEMFCs) are considered to be at the forefront for commercialization for portable and transportation applications because of their high energy conversion efficiency and low pollutant emission. Cost and durability of PEMFCs are the two major challenges that need to be addressed to facilitate their commercialization. The properties of the membrane electrode assembly (MEA) have a direct impact on both cost and durability of a PEMFC. An overview is presented on the key components of the PEMFC MEA. The success of the MEA and thereby PEMFC technology is believed to depend largely on two key materials: the membrane and the electro-catalyst. These two key materials are directly linked to the major challenges faced in PEMFC, namely, the performance, and cost. Concerted efforts are conducted globally for the past couple of decades to address these challenges. This chapter aims to provide the reader an overview of the major research findings to date on the key components of a PEMFC MEA.
Authors: Lan Bo Di
Abstract: Atmospheric-pressure dielectric barrier discharge (DBD) plasma was used to fabricate Pt/C electrocatalysts. The influences of the pretreatment of the activated carbon support and the preparing method on the properties of the Pt/C electrocatalysts were investigated. The composition of the Pt/C samples was characterized by X-ray diffraction (XRD). The electrocatalytic activity of the Pt/C samples was evaluating by measuring the cyclic voltammograms. The results showed that higher dispersion of Pt nanoparticles was obtained on the activated carbon support pretreated by HNO3, and higher reduction rate of Pt ions was obtained in Pt/C prepared by DBD plasma. As a consequence, the Pt/C samples with the activated carbon support pre-oxidized by HNO3 and reduced by DBD plasma exhibited the highest electrocatalytic activity.
Authors: Leslie F. Petrik, Patrick Ndungu, Emmanuel Iheanyechukwu Iwuoha
Abstract: 40% Pt on carbon black was used to make various inks. Compositions were altered by changing the organic component (2-propanol vs 1,2-¬propanediol), the liquid to solid ratio, and addition of Fullerenes to alter electronic properties. Inks were printed onto Nafion® or bond paper substrates using a Presco screen printer. The inks rheological properties were thoroughly characterized, and screen printed electrodes were characterized using optical microscopy, and hall measurements. Ink formulation had a major effect on final film morphology, with high water ratio formulations optimum for the Nafion® substrate and low water ratios ideal for bond paper. The final film integrity influenced sheet hall coefficients with p-type carriers dominating inhomogeneous films, and n – type carriers dominating well formed films. However hall mobility did not correlate with film thickness. Rheological studies showed that increasing the solid ratios and changing the solvent increased the viscosity, and the storage modulus (G') of between 84 and 224 and viscoelastic behaviour of inks correlated with good print quality.
Authors: Takayuki Konishi, Hideki Kawai, Morihiro Saito, Jun Kuwano, Hidenobu Shiroishi
Abstract: The trirutile oxides MTa2O6 (M=Co,Ni,Mg) [MTs] and the substitution products M1-xNxTa2-yLyO6 (N=Mn, L=Sn,Ti,Zr) [M1-xNxTa2-yLy] were prepared by a conventional solid-state reaction. The oxygen reduction reaction (ORR) activities were evaluated with the onset potentials (Eon) of the ORR currents, the disk current densities (iD) and the efficiencies (Eff4) of 4-electron reduction, measured by a rotating ring-disk electrode (RRDE) technique. All the samples showed ORR activities and the Eon values were around +0.8 V vs. RHE in 0.1 M KOH. The CoTa2O6 electrocatalyst showed the best ORR property of the MTs samples: its Eff4 value was as high as ~80%. With substitution of Ti or Sn, the ORR activities of MgTa1.9T0.1O6, CoTa1.8Sn0.2O6 and NiTa1.9Ti0.1O6 were improved in alkaline solution, compared with those of MTa2O6. In acid solution, the same substitution of Ti and Sn resulted in improvement of Eff4, but no significant improvements of Eon and iD.
Authors: Seok Woo Jin, A. Van Neste, Edward Ghali, D. Guay, Robert Schulz
Authors: R. Suresh, K. Giribabu, R. Manigandan, L. Vijayalakshmi, A. Stephen, V. Narayanan
Abstract: We have synthesized Fe3O4 nanoparticles by simple hydrothermal method. The synthesized material was characterized by XRD, FT-IR and FE-SEM etc., The FT-IR spectrum confirms the formation of Fe3O4. XRD confirms the structure and phase purity of the Fe3O4 nanoparticles. The morphological property was characterized by FE-SEM. The synthesized Fe3O4 nanoparticles were used to modify the glassy carbon electrode (GCE) and the modified electrode (n-Fe3O4/GCE) was found to exhibit electrocatalytic activity for the oxidation of uric acid (UA). It shows that the Fe3O4 nanopowder exhibits promising applications in the development of bio-sensors.
Authors: E. Irissou, M. Blouin, Robert Schulz, L. Roué, D. Guay
Authors: S.D. De la Torre, Dariusz Oleszak, F. Almeraya-Calderón, A. Martínez-Villafañe, Roberto Martínez-Sánchez, D. Ríos-Jara, Hiroki Miyamoto
Authors: Mohamed Gabbasa, Kamaruzzaman Sopian
Abstract: The electrodes in Unitized Reversible Fuel Cell system with supported platinum carbon black are reported. However, the electrodes in the system is consist two internal modes; it is electrolyzer and fuel cell mode. A Unitized Reversible Fuel Cell has dual function electrodes are joined in the same cell to reduce the volume and improvement efficiency performance. The electrodes of Unitized Reversible Fuel Cells operating on hydrogen and oxygen which have as high as efficiency at most the applications. Therefore, This article is concentrated on the preparation of bifunctional electrodes as design and material with low platinum loading and supported by platinum carbon black and characterization by using scanning electron microscopy. As well as, survey the latest literature on bifunctional electrodes and electrocatalysts to identify the major problems occur in design of the URFC electrodes.
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