The Experts below are selected from a list of 16263 Experts worldwide ranked by ideXlab platform
Keith Scott - One of the best experts on this subject based on the ideXlab platform.
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a polybenzimidazole ionic liquid Graphite Oxide composite membrane for high temperature polymer electrolyte membrane fuel cells
Journal of Power Sources, 2015Co-Authors: Xiaoteng Liu, Jigui Cheng, Keith ScottAbstract:Graphite Oxide is successfully functionalised by 3-aminopropyltriethoxysilane ionic liquid and used as a filler material in a polybenzimidazole (PBI) membrane for high temperature proton exchange membrane fuel cells. The ionic-liquid-Graphite-Oxide/polybenzimidazole (ILGO/PBI) composite membrane exhibits an appropriate level of proton conductivity when imbibed with phosphoric acid at low phosphoric acid loading, which promotes its use in fuel cells by avoiding acid leakage and materials corrosion. The ionic conductivities of the ILGO/PBI membranes at 175 °C are 0.035 S cm−1 and 0.025 S cm−1 at per repeat units of 3.5 and 2.0, respectively. The fuel cell performance of ILGO/PBI membranes exhibits a maximum power density of 320 mW cm−2 at 175 °C, which is higher than that of a pristine PBI membrane.
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a polybenzimidazole sulfonated Graphite Oxide composite membrane for high temperature polymer electrolyte membrane fuel cells
Journal of Materials Chemistry, 2011Co-Authors: Chenxi Xu, Yuancheng Cao, Xu Wu, Ravi Kumar, Xu Wang, Keith ScottAbstract:Polybenzimidazole/Graphite Oxide (PBI/GO) and PBI/sulfonated Graphite Oxide composite membranes were prepared for high temperature polymer electrolyte membrane fuel cells. The membranes were loaded with phosphoric acid to provide suitable proton conductivity. The PBI/GO and PBI/SGO membranes were characterized by XRD which showed that the d-spacing reflection (001) of SGO in PBI matrix was shifted from 2θ = 11°, meaning that the PBI molecules were intercalated into the SGO layers during the membrane preparation process. A low acid loading level reduced the free acid in the membranes which avoided water loss and thus conductivity loss. The ionic conductivities of the PBI/GO and PBI/SGO membranes, with low acid loading, were 0.027 S cm−1 and 0.052 S cm−1 at 175 °C and 0% humidity. Fuel cell performance with SGO/PBI membranes gave a maximum power density of 600 mW cm−2 at 175 °C.
Chenxi Xu - One of the best experts on this subject based on the ideXlab platform.
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a polybenzimidazole sulfonated Graphite Oxide composite membrane for high temperature polymer electrolyte membrane fuel cells
Journal of Materials Chemistry, 2011Co-Authors: Chenxi Xu, Yuancheng Cao, Xu Wu, Ravi Kumar, Xu Wang, Keith ScottAbstract:Polybenzimidazole/Graphite Oxide (PBI/GO) and PBI/sulfonated Graphite Oxide composite membranes were prepared for high temperature polymer electrolyte membrane fuel cells. The membranes were loaded with phosphoric acid to provide suitable proton conductivity. The PBI/GO and PBI/SGO membranes were characterized by XRD which showed that the d-spacing reflection (001) of SGO in PBI matrix was shifted from 2θ = 11°, meaning that the PBI molecules were intercalated into the SGO layers during the membrane preparation process. A low acid loading level reduced the free acid in the membranes which avoided water loss and thus conductivity loss. The ionic conductivities of the PBI/GO and PBI/SGO membranes, with low acid loading, were 0.027 S cm−1 and 0.052 S cm−1 at 175 °C and 0% humidity. Fuel cell performance with SGO/PBI membranes gave a maximum power density of 600 mW cm−2 at 175 °C.
Mei Liang - One of the best experts on this subject based on the ideXlab platform.
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enhanced mechanical properties of epoxy nanocomposites based on Graphite Oxide with amine rich surface
RSC Advances, 2015Co-Authors: Ya Zhou, Le Li, Yang Chen, Mei LiangAbstract:Functional Graphite Oxide (DGO) with amine-rich surface was synthesized through chemically grafting flexible poly(oxypropylene)diamine, and its epoxy (EP) composites were prepared. Fourier transform infrared spectra (FTIR) etc. confirmed the realization of chemical functionalization of DGO. The covalent functionalization of Graphite Oxide (GO) with poly(oxypropylene)diamine was favorable to its homogeneous dispersion in epoxy matrix. Meanwhile, the strong covalent interface formed between epoxy and DGO promoted the stress transfer. The addition of 0.3 wt% DGO increased the tensile strength, flexural strength, elongation at break and toughness of the epoxy resins by 20%, 40%, 90% and 145%, respectively. This showed higher improvements than those addition of GO. Therefore, significant improvements both in the strength and toughness of epoxy nanocomposites were achieved by the addition of trace DGO.
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curing characteristics of an epoxy resin in the presence of functional Graphite Oxide with amine rich surface
Thermochimica Acta, 2015Co-Authors: Le Li, Zhong Zeng, Mei LiangAbstract:Abstract Functional Graphite Oxide (DGO) with amine-rich surface was successfully prepared through the amidation reaction and characterized by X-ray diffraction analyses (XRD), Fourier transform infrared spectra (FTIR) and Raman spectra. The effects of functional Graphite Oxide on the curing kinetics of epoxy (EP) were investigated by means of differential scanning calorimetry (DSC). The curing kinetic parameters of EP, EP/Graphite Oxide (GO) and EP/functional Graphite Oxide were obtained. There was not much difference in total heat of reaction ΔH and peak temperature Tp with the incorporation of GO or DGO. However, the activation energy, Ea, and the overall order of reaction m + n were enhanced. Comprehensive kinetic analyses indicated that the incorporation of GO sheets brought in an effect of inhibition on curing process. While the inhibition effect weaken when the GO is modified with amine-rich surface. The possible curing mechanism and reaction pathways were proposed to provide a reasonable explanation.
Xiaoteng Liu - One of the best experts on this subject based on the ideXlab platform.
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a polybenzimidazole ionic liquid Graphite Oxide composite membrane for high temperature polymer electrolyte membrane fuel cells
Journal of Power Sources, 2015Co-Authors: Xiaoteng Liu, Jigui Cheng, Keith ScottAbstract:Graphite Oxide is successfully functionalised by 3-aminopropyltriethoxysilane ionic liquid and used as a filler material in a polybenzimidazole (PBI) membrane for high temperature proton exchange membrane fuel cells. The ionic-liquid-Graphite-Oxide/polybenzimidazole (ILGO/PBI) composite membrane exhibits an appropriate level of proton conductivity when imbibed with phosphoric acid at low phosphoric acid loading, which promotes its use in fuel cells by avoiding acid leakage and materials corrosion. The ionic conductivities of the ILGO/PBI membranes at 175 °C are 0.035 S cm−1 and 0.025 S cm−1 at per repeat units of 3.5 and 2.0, respectively. The fuel cell performance of ILGO/PBI membranes exhibits a maximum power density of 320 mW cm−2 at 175 °C, which is higher than that of a pristine PBI membrane.
Ilhan A. Aksay - One of the best experts on this subject based on the ideXlab platform.
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raman spectra of Graphite Oxide and functionalized graphene sheets
Nano Letters, 2008Co-Authors: Konstantin N Kudin, Ilhan A. Aksay, Hannes C. Schniepp, Robert K Prudhomme, Bulent Ozbas, Roberto CarAbstract:We investigate Raman spectra of Graphite Oxide and functionalized graphene sheets with epoxy and hydroxyl groups and Stone−Wales and 5−8−5 defects by first-principles calculations to interpret our experimental results. Only the alternating pattern of single−double carbon bonds within the sp2 carbon ribbons provides a satisfactory explanation for the experimentally observed blue shift of the G band of the Raman spectra relative to Graphite. To obtain these single−double bonds, it is necessary to have sp3 carbons on the edges of a zigzag carbon ribbon.
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intercalation and stitching of Graphite Oxide with diaminoalkanes
Langmuir, 2007Co-Authors: Margarita Herreraalonso, Michael J. Mcallister, Ilhan A. Aksay, Ahmed Abdala, Robert K PrudhommeAbstract:The intercalation reaction of Graphite Oxide with diaminoalkanes, with the general formula H2N(CH2)nNH2 (n = 4−10), was studied as a method for synthesizing pillared Graphite with tailored interlayer spacing. Interlayer spacings from 0.8 to 1.0 nm were tailored by varying the size of the intercalant from (CH2)4 to (CH2)10. X-ray diffraction and infrared spectroscopy were used to confirm intercalation, and the frequency of the CH2 stretch confirmed that the intercalants are in a disordered state, with an important contribution from the gauche conformer. Sequential intercalation of diaminoalkanes followed by dodecylamine demonstrated the inability of these “stitched” systems to undergo expansion along the c-direction, indicative of cross-linking. Finally, the reaction of Graphite Oxide with diaminoalkanes under reflux and for extended periods (>72 h) resulted in the chemical reduction of the Graphite Oxide to a disordered graphitic structure.
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Functionalized single graphene sheets derived from splitting Graphite Oxide
Journal of Physical Chemistry B, 2006Co-Authors: Hannes C. Schniepp, Je Luen Li, Margarita Herrera-alonson, Dudley A. Seville, Michael J. Mcallister, Roberto Car, Hiroaki Sai, Robert K. Prud'homme, Douglas H Adamson, Ilhan A. AksayAbstract:A process is described to produce single sheets of functionalized graphene through thermal exfoliation of Graphite Oxide. The process yields a wrinkled sheet structure resulting from reaction sites involved in oxidation and reduction processes. The topological features of single sheets, as measured by atomic force microscopy, closely match predictions of first-principles atomistic modeling. Although Graphite Oxide is an insulator, functionalized graphene produced by this method is electrically conducting.
