State of Understanding of Nafion

Mauritz, Kenneth A.; Moore, Robert B.

doi:10.1002/chin.200450273

Cited by 390 publications

(635 citation statements)

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“…From to this result, the activity sequence of Nafion resins, Amberlyst resins and sulfated carbon mesoporous materials can also be rationalized by their acid strength. According to literature, Nafion is perfluorinated sulfonic acid resin that is often denoted as a superacid Mauritz and Moore, 2004;Weingarten et al, 2011). Amberlyst is sulfonicacid-functionalized cross-linked polystyrene resin Weingarten et al, 2011).…”

Section: Resultsmentioning

confidence: 99%

“…However, sulfated mesoporous carbon is amorphous carbon bearing SO 3 H, COOH and phenolic OH groups which function as acid sites (Suganuma et al, 2008). In Nafion resins, the acid strength of SO 3 H group is enhanced by the presence of fluorine, which makes its acid strength higher than Amberlyst resins and sulfated mesoporous carbons (Mauritz and Moore, 2004). Another possibility for the higher activity of Nafion resins may be the higher acid site accessibility which is also very important in acid catalyzed reactions.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of renewable diesel with the 2-methylfuran, butanal and acetone derived from lignocellulose

Yang

et al. 2013

Bioresource Technology

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis of renewable diesel with the 2-methylfuran, butanal and acetone derived from lignocellulose

Yang

et al. 2013

Bioresource Technology

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“…Details of fabrication procedures are described in Supplementary Information, section 1. The resulting free-standing membranes were checked for the absence of pinholes and defects (Supplementary Information, sections 1-3) and spin coated from both sides with Nafion, a polymer that exhibits high proton and negligible electron conductivity 25 . Finally, two proton injecting PdH x electrodes 26,27 were deposited onto Nafion from both sides of the wafer ( Supplementary Figs 1 and 2).…”

mentioning

confidence: 99%

“…1a, 2D crystals effectively serve as atomically thin barriers between two Nafion spaces. For electrical measurements, samples were placed in a hydrogen-argon atmosphere at 100% humidity, which ensured high conductivity of Nafion films 25,26 . Examples of I-V characteristics measured for devices incorporating monolayers of graphene, hBN and MoS 2 are shown in Fig.…”

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confidence: 99%

Proton transport through one-atom-thick crystals

Lozada-Hidalgo

Wang

et al. 2014

Nature

742

838

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Graphene is impermeable to all gases and liquids 1-3 , and even such a small atom as hydrogen is not expected to penetrate through graphene's dense electronic cloud within billions of years 3-6 . Here we show that monolayers of graphene and hexagonal boron nitride (hBN) are unexpectedly permeable to thermal protons, hydrogen ions under ambient conditions. As a reference, no proton transport could be detected for a monolayer of molybdenum disulfide, bilayer graphene or multilayer hBN. At room temperature, monolayer hBN exhibits the highest proton conductivity with a low activation energy of 0.3 eV but graphene becomes a better conductor at elevated temperatures such that its resistivity to proton flow is estimated to fall below 10 -3 Ohm per cm 2 above 250°C. The proton barriers can be further reduced by decorating monolayers with catalytic nanoparticles. These atomically thin proton conductors could be of interest for many hydrogen-based technologies.Graphene has recently attracted renewed attention as an ultimately thin membrane that can be used for development of novel separation technologies (for review, see refs. 7,8). If perforated with atomic or nanometer accuracy, graphene may provide ultrafast and highly selective sieving of gases, liquids, ions, etc. 2,9-19 However, in its pristine state, graphene is absolutely impermeable for all atoms and molecules moving at thermal energies [1][2][3][4][5][6][7] . Theoretical estimates for the kinetic energy E required for an atom to penetrate through monolayer graphene vary significantly, depending on the employed model, but even the smallest literature value of 2.4 eV for atomic hydrogen 3-6 is 100 times larger than typical k B T which ensures essentially an impenetrable barrier (k B is the Boltzmann constant and T the temperature). Therefore, only accelerated atoms are capable of penetrating through the one atom thick crystal 20,21 . The same is likely to be valid for other two dimensional (2D) crystals 22,23 , although only graphene has so far been considered in this context. Protons can be considered as an intermediate case between electrons that tunnel relatively easily through atomically thin barriers 24 and small atoms. It has been calculated that E decreases by a factor of up to 2 if hydrogen is stripped of its electron 4,5 . Unfortunately,

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“…Nafion® membranes contains negatively charged sulfonated groups in the backbone of the polymer chains, which explains the high level of proton conductivity, while also showing a significant, undesirable affinity for other cations, rather than protons [14]. In general, MFCs are operated with a pH increasing as consequence of the amount of cations (Na + , K + , Ca 2+ , Mg 2+ and NH 4+ ) contained in the growth medium, where they are typically present in concentrations about 100 times as high as that of protons.…”

Section: Introductionmentioning

confidence: 99%