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Song M.-A.,Myongji University | Ha S.-I.,Myongji University | Park D.-Y.,Myongji University | Ryu C.-H.,Hoseo University | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2013

Covalently cross-linked SPEEK/Cs-TPA/CeO2 composite membrane was prepared for the polymer electrolyte membrane water electrolysis. Tungstophosphoric acid (TPA) with a cesium was added to the SPEEK to increase proton conductivity. CeO2 was used to scavenge free radicals which attack the membrane in the water electrolysis and to improve the durability of the membrane. The composite membrane featured the electrochemical characteristics, such as 0.130 S/cm of proton conductivity at 80 °C, and 2.324 meq./g-drymemb. of ion-exchange capacity. Pt(NH3) 4Cl2, Pd(NH3)4Cl2, RhCl3 and Co(NH6)4Cl3 were used to prepare a variety of the membrane electrode assemblies (MEAs) as electrocatalytic precursors. Electrochemical activity surface area (ESA) of the PtePd electrode prepared with 2 mM Pt(NH3)4Cl2 and 2 mM Pd(NH3)4Cl2 showed the best properties of 26.2 m2/g with CL-SPEEK/Cs-TPA/CeO2 membrane. In water electrolysis performance, the cell voltage of Pd/PEM/PtePd MEA with CL-SPEEK/Cs-TPA/CeO2(1%) composite membrane showed cell property of 1.82 V at 1 A cm-2 and 80 °C. Copyright © 2013, Hydrogen Energy Publications, LLC.

Lee K.-M.,Myongji University | Woo J.-Y.,Myongji University | Jee B.-C.,Myongji University | Hwang Y.-K.,Myongji University | And 4 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2011

In order to improve the mechanical properties while maintaining electrochemical characteristics, engineering plastic of poly(ether ether ketone) as polymer matrix was sulfonated and the organic-inorganic blend composite membranes was prepared by loading 20-50% of HPAs, including tungstophosphoric acid (TPA), molybdophosphoric acid (MoPA) and tungstosilicic acid (TSiA). And then, these composite membranes were covalently cross-linked with the variation of 0.005-0.015. mL of cross linking agent contents (CL-SPEEK/HPA). Also, the characteristics of membrane electrolyte assembly (MEA) were measured in polymer electrolyte membrane electrolysis (PEME) cells. Although cross-linking decreased the number of sulfonic acid groups available for proton transfer in the membrane, the addition of cross-linking agent and HPAs significantly improved the mechanical and electrochemical properties of the membrane.Consequently, the optimum conditions of CL-SPEEK/HPAs with 0.01. mL of cross-linking agent content were established and electrochemical characteristics, such as ion conductivity, was in the order of magnitude: CL-SPEEK/TPA30 (30. wt%) < CL-SPEEK/MoPA40 < CL-SPEEK/TSiA30 and mechanical characteristics such as tensile strength: Nafion117 < CL-SPEEK/TSiA30 < CL-SPEEK/MoPA40 < CL-SPEEK/TPA30. With increasing cross-linking agent content, tensile strength increased and ion conductivity decreased. CL-SPEEK/MoPA40 showed the best electrocatalytic activity of cell voltage 1.71. V at 80°C among the prepared composite membranes. However, in consideration of high water content, low anti-oxidative property and weak mechanical properties of CL-SPEEK/MoPA40 and CL-SPEEK/TSiA30 membranes, in spite of its high proton conductivity and electrocatalytic activity, it is expected that the CL-SPEEK/TPA30 (1.75. V) was suitable as an alternative membrane in large scale polymer electrolyte membrane electrolysis system. The dual effect of higher proton conductivity and electrocatalytic activity with the addition of HPAs, causes a synergy effect. © 2011 The Korean Society of Industrial and Engineering Chemistry.

Woo J.-Y.,Myongji University | Lee K.-M.,Myongji University | Jee B.-C.,Myongji University | Ryu C.-H.,Myongji University | And 5 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2010

Membrane electrode assemblies (MEAs) of covalently cross-linked sulfonated poly(ether ether ketone) (CL-SPEEK)/heteropolyacids (HPAs) composite polymer with platinum-based alloys such as Pt-Ru-Co and Pt-Ru-Ni were prepared and their electrochemical properties for water electrolysis were investigated. The HPAs, which were used in the composite membranes, were tungstophosphoric acid (TPA) (the part of TPA data was permitted by the previous authors), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA). The MEAs with Pt-Co, Pt-Ru-Co, and Pt-Ru-Ni in the anode catalyst layer were prepared by means of a non-equilibrium impregnation-reduction (I-R) method. The electrocatalytic properties of composite membranes, such as the cell voltage and coulombic charge in CV, were in the following order: CL-SPEEK/MoPA40>CL-SPEEK/TPA30>CL-SPEEK/TSiA40 (wt%). For the optimum cell applications of water electrolysis, the cell voltage of Pt/PEM/Pt-Ru-Co (Electrodeposited (Dep)-MoPA) MEA with a CL-SPEEK/MoPA40 membrane was 1.70V at 80°C and 1Acm-2, and this voltage carried a value lower than that of 1.81V of Nafion 117. In addition, the observed activity of Pt-Ru-Co (75:12:13 by EDX) is a little higher than that of Pt-Ru-Ni (79:10:11 by EDX). The mean coulombic charge and activity enhancement of Pt-Ru-Co catalysts, with and without electrodeposition, showed the same CV profiles of the Pt-Ru-Co catalysts and were in the following order: Nafion 117

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