Proton conductivity of biopolymer–platinum nanoparticle composite under high humidity
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A κ-carrageenan–Pt nanoparticle composite (Cg–Pt) was synthesized and its proton conductivity was examined by a complex-plane impedance method. The synthesized Cg–Pt was characterized by transmission electron microscope (TEM) observation, powder X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) absorption measurements, and thermogravimetry/mass spectrometry (TG/MS) analysis. It was revealed that the a.c. electrical conductivity of Cg–Pt strongly depends on relative humidity (RH) and exceeds the conductivity of Cg under conditions of high humidity. From the temperature dependence of the a.c. conductivity, activation energies for protonic conduction were estimated to be 0.47 and 0.34 eV for Cg–Pt and Cg, respectively. The origin of the differences in the conductivities and activation energies are discussed.
KeywordsProton Conductivity Nanoparticle Composite Polymer Electrolyte Fuel Cell Proton Migration High Humidity Condition
This work was partly supported by a Grant-in-Aid for Scientific Research (No. 17750060) and Nanotechnology Network Project (Kyushu-area Nanotechnology Network) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and by the Japan Securities Scholarship Foundation, CASIO Science Promotion Foundation, Kansai Research Foundation for technology promotion, and Nippon Sheet Glass Foundation for Materials Science and Engineering.
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