Imidazolium-based anion exchange membranes for alkaline anion fuel cells; Elucidation of the morphology and the interplay between the morphology and properties

Zhao, Y.; Yoshimura, Kimio; Shishitani, Hideyuki*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Koizumi, Satoshi*; Szekely, N.*; Radulescu, A.*; Richter, D.*; Maekawa, Yasunari

Soft Matter, 12(5), p.1567 - 1578, 2016/02

https://doi.org/10.1039/C5SM02724A

Imidazolium cation based anion-conducting electrolyte membranes prepared by radiation induced grafting for direct hydrazine hydrate fuel cells

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Journal of the Electrochemical Society, 161(9), p.F889 - F893, 2014/06

https://doi.org/10.1149/2.0511409jes

Graft-type anion-conducting electrolyte membranes (AEMs) with imidazolium cations on graft polymers were synthesized through radiation-induced graft polymerization of -vinylimidazole (NVIm) on poly(ethylene-co-tetrafluoroethylene) (ETFE) films, followed by -propylation and ion-exchange reactions. The -propylation proceeded quantitatively, whereas the ion-exchange reactions in 1 M KOH at 60C were accompanied by partial -elimination of the imidazolium cations(AEM2), which exhibited an ion-exchange capacity (IEC) of 0.85 mmol g and ionic conductivity of 10 mS cm. AEM2 showed alkaline stability at 60C but it gradually degraded at 80C for ca. 150 h. The copolymer-type AEM (AEM3) with an IEC of 1.20 mmol g was prepared through the copolymerization of NVIm with styrene on ETFE films, followed by the same -propylation and ion-exchange reactions. AEM3 was shown higher alkaline durability in 1 M KOH at 80C. As a result, it exhibited higher conductivity (10 mS cm) for 250 h. Therefore, alkylimidazolium cations in copolymer grafts are a promising anion conducting group for alkaline-durable AEMs. A maximum power density of 75 mW cm is obtained for AEM3 in a direct hydrazine hydrate fuel cell.

Counter-anion effect on the properties of anion-conducting polymer electrolyte membranes prepared by radiation-induced graft polymerization

Koshikawa, Hiroshi; Yoshimura, Kimio; Sinnananchi, W.; Yamaki, Tetsuya; Asano, Masaharu; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Macromolecular Chemistry and Physics, 214(15), p.1756 - 1762, 2013/08

https://doi.org/10.1002/macp.201300225

Graft-type anion-conducting polymer electrolyte membranes were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization with trimethylamine to evaluate the counter anion effects on fuel cell properties. The hydroxide form was maintained in -saturated water to prevent the bicarbonate formation. The hydroxide form showed conductivity and water uptake four and two times higher than the chloride and bicarbonate forms. The hydroxide form is thermally and chemically less stable, resulting in the tendency to absorb water and to convert to the bicarbonate form.

Optical detection of organic hydrides with platinum-loaded tungsten trioxide

Yoshimura, Kimio; Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito

Journal of Physics and Chemistry of Solids, 73(5), p.696 - 698, 2012/05

https://doi.org/10.1016/j.jpcs.2012.01.017

Tungsten trioxide powder with loading 0.1wt% platinum (Pt/WO) was prepared for opticaldetection of organic hydrides such as cyclohexane, decalin by impregnation with PtCl and subsequent calcination in N gas at 500C. The SEM observation of Pt/WO shows that the Pt particles with mean diameters of 80-100 nm were on the surface of the WO powder. The Pt/WO showed coloration for 13% cyclohexane at higher 100C and for 1.3% cyclohexane at 200C. The in-situ XRD results of the Pt/WO in coloring/bleaching change indicate that the coloring of Pt/WO was caused by transformation of WO to tungsten bronze. The analysis of reacted gas demonstrates that Pt on WO produces only hydrogen and benzene through dehydrogenation of cyclohexane over 100C. It was founded that the Pt/WO has potential of optical detection of organic hydrides by heating at higher 100C.

Dehydrogenation catalyst for optical organic-hydride detection

Yoshimura, Kimio; Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito

Applied Surface Science, 257(9), p.4428 - 4431, 2011/02

https://doi.org/10.1016/j.apsusc.2010.12.079

no abstracts in English

Alkaline durable anion exchange membranes synthesized by radiation-induced grafting

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Sampei, Fumihiro*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

no journal, , 

no abstracts in English

Synthesis of alkaline durable anion exchange membranes by radiation-induced grafting for hydrazine hydrate fuel cell

Yoshimura, Kimio; Sinananwanich, W.*; Koshikawa, Hiroshi; Asano, Masaharu; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; et al.

no journal, , 

no abstracts in English

Synthesis and properties of metal-chelating polycarbosilane polymer prepared by radiation grafting

Yoshimura, Kimio; Sugimoto, Masaki; Yoshikawa, Masahito

no journal, , 

Polycarbosilane (PCS) polymer with the chelated nickel or palladium was synthesized by the radiation-graft polymerization method. It was found that radicals induced in PCS polymers by electron beam irradiation behave as the sites of graft reaction between PCS polymer and glycidyl methacrylate (GMA) and the degree of graft polymerization was observed to be in proportion to the absorbed dose. After the chelate group was produced in the polymer chain derived from GMA by the reaction with diethylenetriamine, nickel or palladium was introduced into the chelate groups by soaking the solutions of corresponding metal salts. The obtained PCS polymer with the chelated nickel or palladium was fired at 973 K or 1373 K to produce silicon carbide (SiC) ceramics containing nickel or palladium and physical characteristics were measured by XRD, SEM and EDS analysis. As the results, it was found that nickel or palladium is isolated as fine metal grains on the SiC ceramics, i. e., the nickel grains are dispersed with carbon and palladium grains are cohesive on the surface of SiC ceramics.

Preparation of anion-exchange membranes for fuel cell applications by -ray pre-irradiation grafting; Effect of the structure of quaternary ammonium ions

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Yoshimura, Kimio; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

We investigated the effect of the length of the linear chain on the structure of quaternary ammonium ions on the membrane properties such as durability of ion conductivity. Graft polymerization was performed by immersing the pre-irradiated ETFE film in the CMS solution. The ETFE-g-CMS film was then quaternized in four different tertiary amines, that is, trimethylamine (n = 1), dimethylethylamine (n = 2), n-butyldimethylamine (n = 4) and n-hexyldimethylamine (n = 6) solutions. The n dependence of the OH conductivity and chemical durability, which was represented by a residual percentage of the conductivity after treatment with a Fenton solution. When n increased from 1 to 6, the OH conductivity decreased slightly, but it still stayed 20 mS/cm for n = 6. The chemical durability seemed to increase eight-fold at the same time. The chemical attack by hydroxyl radicals on the quaternary ammonium ions would be controlled by hydrophobicity and steric hindrance of the alkyl group.

Irradiation-induced change in optical absorption spectra of Ag and Au nanoparticles on SiO substrate

Kawaguchi, Kazuhiro; Takahiro, Katsumi*; Yamamoto, Shunya; Hakoda, Teruyuki; Yoshimura, Kimio; Yoshikawa, Masahito

no journal, , 

no abstracts in English