Papers by Keyword: Proton Conductivity

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Authors: Katsuya Sakamoto, Hidenobu Shiroishi, Takaaki Shirai, Shunsuke Satou, Morihiro Saito, Jun Kuwano
Abstract: The ternary oxide compositions xZrO2-(0.5–x/2)Al2O3-yP2O5(x=0.8, 0.9, 0.95, 1.0; y=1.0, 1.2, 1.4) and 0.9ZrO2-0.05In2O3-1.4P2O5, xSiO2-(0.5–x/2)Al2O3-1.4P2O5(x=0.9, 1.0) were synthesized by sol-gel methods, and their conductivities were investigated by ac-impedance spectroscopy. The conductivity increased with increasing P2O5 content and with decreasing heat-treatment temperature. The maximum conductivities reached over 10-2 Scm-1 at 150°C for 0.9ZrO2-0.05Al2O3-1.4P2O5 and at 225°C for 0.9SiO2-0.05Al2O3-1.4P2O5.
Authors: Yu Han Li
Abstract: Linear and kinked bulky monomers were incorporated into the main chain of a polyimide in order to investigate the effect of kinked versus linear polymers on membrane properties such as water uptake and proton conductivity. Polymers prepared using linear 1,4-bis (4-aminophenoxy)-naphthyl-2,7-disulfonic acid (BAPNDS), SPI-N, and using kinked 2,2’-bis (p-aminophenoxy)-1,1’-binaphthyl-6,6’-disulfonic acid (BNDADS), SPI-BN, were cast into membranes. All the copolymers showed excellent solubility and good film-forming capability. Membranes are thermally stable up to 300 °C under air. For SPI-BN, the nonplanar binaphthyl group result in polymer chain relaxation and produce large water uptake. However, the conductivity of kinked, SPI-BN membranes is lower than those prepared from SPI-N for a given IEC but water uptakes are higher. This might be related to substitution position of the sulfonic acid groups and the microstructure. Sulfonic acid group were located at the same side of the main chain will be favorable for forming hydrophilic clusters, thus better proton conductivity performance would be achieved.
Authors: V.B. Silva, V.S. Silva, L.M. Madeira, Suzana Pereira Nunes, A. Mendes
Abstract: Electrochemical impedance experiments were carried out in order to study the influence of the ZrO2 inorganic incorporation on the proton conductivity of sulfonated poly(ether ether ketone) (sPEEK) membranes. The impedance data was fitted to an extension of Randles’ circuit, within the inorganic content and temperature ranges considered. The model fits quite well for ZrO2 loads up to 10 wt.%. Such a model allows for characterizing the diffusion phenomena (Warburg) of the membrane electrode assembly (MEA), membrane and electrodes resistances, capacitive and inductive behavior. Proton conductivity was obtained from the impedance spectra and it was observed that it increases with temperature and decreases with the inorganic content. As a general trend, the Warburg parameter decreases slightly with the temperature, except for the 5 wt. % ZrO2 membrane that suffers a more pronounced influence. The Warburg parameter also decreases with the ZrO2 content.
Authors: Yoshihide Honda, N. Kimura, P.K. Pujari, G. Isoyama, Seiichi Tagawa, H. Miyauchi, Y. Shibahara, H.S. Sodaye, Y. Akiyama, Y. Izumi, S. Nishijima
Abstract: Positron annihilation techniques were applied for irradiated Nafion-117 to investigate deterioration process in PEM. There were no significant changes in lifetime of positron/positronium, whereas the S-parameter showed fairly good correlation with proton conductivity.
Authors: Ayhan Bozkurt, Ayşe Aslan
Abstract: Novel proton conducting nanocomposite membranes included binary and ternary mixtures of acid modified nanotitania particles particles with polymers such as poly (vinyl alcohol) (PVA),pol (vinyl phosphonic acid), sulfonated polysulfone (SPSU) and poly (1-vinyl 1,2,4-triazole) (PVTri) . The interaction of functional nanoparticles with the host matrix were searched by FT-IR spectroscopy. The homogeneous distribution of functional nanoparticles in the membranes was confirmed by SEM micrographs. The spectroscopic measurements and water/methanol uptake studies suggested a complexation between polymers and sulphonic acid that inhibited the leaching out of acidic units. The TGA results verified that the presence of modified nanoparticles in the composite membranes the thermel stability of the membranes enhanced up to above 200 °C.
Authors: B. Narayanamoorthy, B. Dineshkumar, S. Balaji
Abstract: The amino functionalized magnesium phyllosilicate clay (AC) intercalated over PVA-Nafion hybrid nanocomposite membranes were prepared by sol-gel method. The free standing membranes were obtained by solution recasting. The composition of clay materials such as AC and montmorillonite (MMT) was varied between 2-10 wt.% with respect to PVA-Nafion content. The molecular interactions and surface morphology of nanocomposite membranes were investigated by FT-IR and SEM analyses respectively. The thermal and mechanical stabilities of nanocomposite membranes were studied using TGA and Nanoindentation techniques. For 6 wt. % AC/PVA-Nafion, TGA results showed no appreciable mass change up to 380 °C and hardness calculated from nanoindentation studies was nearly 30 % higher than the other compositions. An improved conductivity was obtained for 6 wt. % AC/PVA-Nafion (1.4×10-2 S/cm) compared to pure Nafion (1.2×10-2 S/cm) and PVA-Nafion and MMT/PVA-Nafion composite membranes. From these studies, we observed that 6 wt. % AC/PVA-Nafion membrane possessed a good conductivity with higher thermal and mechanical stabilities.
Authors: H. Ilbeygi, A.F. Ismail, M.M. Nasef, J. Jaafar, E. Jalalvandi, P. Panahi
Abstract: This study was to investigate the properties of the sulfonated poly(ether ether ketone) (SPEEK) nanocomposite membranes filled with Cloisite 15A® clay, in the presence of 2,4,6 triaminopyrimidine (TAP) as a compatibilizer. The membranes were prepared via solution intercalation method, before they were subjected to performance tests in the temperature range of 27 to 80 oC for comparison with Nafion® 117. The SPEEK membranes were then utilized to measure the open circuit voltage (OCV) and power density for direct methanol fuel cell (DMFC) applications in the temperature range of 27 to 60 oC. The best data obtained, among all the tested membranes, were methanol permeability of 0.52 ×10-6 cm2s-1 and proton conductivity of 47 mScm-1 with the methanol selectivity of 9.1 × 104, even at a high temperature of 60oC.
Authors: Hirokazu Munakata, Hiroto Chiba, Kaoru Dokko, Jun Ichi Hamagami, Takashi Takei, Kiyoshi Kanamura
Abstract: A new proton-conducting membrane was prepared consisting of uniformly macroporous silica matrix and a proton-conducting gel polymer, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). Three-dimensionally ordered macroporous silica membrane was fabricated by use of a colloidal template method with mono-dispersed polystyrene beads. Surface sulfonation of the pores in the silica matrix was performed by using 1,3-propanesultone. The sulfonated silica matrix exhibited about 400 times higher proton conductivity than unmodified one. The proton conductivity of the composite membrane was also successfully enhanced by using the sulfonated silica matrix.
Authors: Yu Feng Lin, Chen Chi M. Ma, Yao Yu Lin, Chuan Yu Yen, Chih Hung Hung
Abstract: A novel organic–inorganic mesoporous silica functionalized with perfluoroalkylsulfonic acid groups analogous to that of Nafion® has been prepared. A condensation reaction between surface silanol groups of the mesoporous silicas and 1,2,2-trifluoro-2-hydroxy-1-trifluoromethylethane sulfonic acid Beta-sultone was conducted. High proton conducting sulfonated poly(ether ether ketone) (sPEEK)/ functionalized mesoporous silica composite membranes were prepared through homogeneous dispersive mixing and solvent casting method. In the study, proton conductivity (σ) of composite membrane is increased from 0.01 to 0.038 (S/cm) as the modified mesoporous silica content is increased from 0 to 5 wt. %. It is found that the ion exchange capacity (IEC) is increased from 1.54 to 1.70 (meq/g) as the modified mesoporous silica content is increased from 0 to 5 wt. %. From morphology investigation, it is found that incorporation of modified mesoporous silica by rotary vacuum evaporation enables the preparation of homogeneous membranes. The membranes present a good adhesion between inorganic domains which could be used for fuel cell applications.
Authors: Liang Ming Xiong, Masayuki Nogami
Abstract: As an alternative to a solid-state electrolyte for proton exchange membrane fuel cells (PEMFCs), ordered mesoporous membranes (OMMs) were prepared using a sol-gel technique, followed by a deep-UV irradiation. Structure and impedance spectroscopy analyses revealed that the porous architecture and proton conductivity of OMMs were influenced by the nature of the substrates. Compared with hydrophilic substrate, hydrophobic substrate was beneficial to an accessible porous architecture in the interface layer and an increase of proton conductivity of the whole membrane. The proton conductivity of the OMMs was up to 10-3 S cm-1.
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