Nafion

About: Nafion is a research topic. Over the lifetime, 9110 publications have been published within this topic receiving 320865 citations.

Hydrogen-Bonded Organic Frameworks (HOFs): A New Class of Porous Crystalline Proton-Conducting Materials.

Abstract: Two porous hydrogen-bonded organic frameworks (HOFs) based on arene sulfonates and guanidinium ions are reported. As a result of the presence of ionic backbones appended with protonic source, the compounds exhibit ultra-high proton conduction values (σ) 0.75× 10−2 S cm−1 and 1.8×10−2 S cm−1 under humidified conditions. Also, they have very low activation energy values and the highest proton conductivity at ambient conditions (low humidity and at moderate temperature) among porous crystalline materials, such as metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). These values are not only comparable to the conventionally used proton exchange membranes, such as Nafion used in fuel cell technologies, but is also the highest value reported in organic-based porous architectures. Notably, this report inaugurates the usage of crystalline hydrogen-bonded porous organic frameworks as solid-state proton conducting materials.

Nanofiltration (NF) membranes: the next generation separators for all vanadium redox flow batteries (VRBs)?

Abstract: NF membranes, as an alternative to traditional ion exchange membranes, were first proposed and successfully prepared for VRBs based on a totally new concept of tuning the vanadium/proton selectivity viapore size exclusion. The results showed that membranes show increasing vanadium ion/proton (V/H) selectivity with decreasing pore size distribution. VRBs assembled with prepared NF membranes exhibited comparable performance to that of commercialized Nafion. The concept could potentially overcome the traditional restriction from ion exchange membranes and provide much more material options for VRB membranes.

A Critical Revision of the Nano-Morphology of Proton Conducting Ionomers and Polyelectrolytes for Fuel Cell Applications

Abstract: A few aspects of the nano-morphology of hydrated Nafion and other ionomers and polyelectrolytes in their acid form are revisited by examining the evolution of small angle X-ray scattering (SAXS) data which are recorded for a wide range of water volume fractions (Φwater ≈ 7–56 vol%). A consistency check with the recent “parallel cylinder model” discloses that this is most likely biased by a large uncertainty of the experimentally determined water content. We rather find our data to be consistent with locally flat and narrow (around 1 nm) water domains. The formation of relatively thin water “films” is suggested to be a common feature of many ionomers and polyelectrolytes, and the underlying driving force is most likely electrostatics within these highly dissociated systems. The water films may act as a charged (e.g., with positive protonic charge carriers) “glue”, keeping together the oppositely charged polymer structures. While this interaction tends to produce flat morphologies, the formation process is suggested to be constraint by limited conformational degrees of freedom of the corresponding polymer and the interactions between polymer backbones. This may leave severe tortuosities on larger scales which depend on the sample history (including swelling, de-swelling, aging, stretching, and pressing).

Polymer Films on Electrodes. 5. Electrochemistry and Chemiluminescence at Nafion-Coated Electrodes

Abstract: Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Polymer films on electrodes. 5. Electrochemistry and chemiluminescence at Nafion-coated electrodes Israel Rubinstein, and Allen J. Bard J. Am. Chem. Soc., 1981, 103 (17), 5007-5013• DOI: 10.1021/ja00407a006 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on February 13, 2009