Ionic Conductivity of C60-Based Solid Electrolyte

Non-Fluorinated Polymer Composite Proton Exchange Membranes for Fuel Cell Applications - A Review

The critical component of a proton exchange membrane fuel cell (PEMFC) system is the proton exchange membrane (PEM). Perfluorosulfonic acid membranes such as Nafion are currently used for PEMFCs in industry, despite suffering from reduced proton conductivity due to dehydration at higher temperatures. However, operating at temperatures below 100 °C leads to cathode flooding, catalyst poisoning by CO, and complex system design with higher cost. Research has concentrated on the membrane material and on preparation methods to achieve high proton conductivity, thermal, mechanical and chemical stability, low fuel crossover and lower cost at high temperatures. Non-fluorinated polymers are a promising alternative. However, improving the efficiency at higher temperatures has necessitated modifications and the inclusion of inorganic materials in a polymer matrix to form a composite membrane can be an approach to reach the target performance, while still reducing costs. This review focuses on recent research in composite PEMs based on non-fluorinated polymers. Various inorganic fillers incorporated in the PEM structure are reviewed in terms of their properties and the effect on PEM fuel cell performance. The most reliable polymers and fillers with potential for high temperature proton exchange membranes (HTPEMs) are also discussed.

Oxidation route dependent proton conductivities of oxidized fullerenes

Proton conductivities of oxidized fullerenes from different types of oxidizing agents were measured. Among all, NaOH treated fullerenes were showed higher proton conductivity.

Complete set of critical points on the C60H+ potential energy surface

To calculate the proton affinity of fullerene (C60), density functional theory was used to determine the global minimum energy structures of both fullerene and its protonated forms. Vibrational frequency calculations were used to check the nature of these predicted structures. In the protonation of C60 in the gas phase, the proton preferentially lies above the carbon atoms at a distance of 1.10 A, which suggests a bond of covalent nature. The proton affinity for fullerene was calculated as 201.8 kcal/mol, compared with the experimental value between 204 and 207 kcal/mol obtained by proton-transfer bracketing studies using Fourier transform mass spectrometry. All five transition states for intramolecular proton transfer in fullerene were found, three for the first time. The activation energy (E(a)) barriers for proton migration were calculated and ranged from 27 to 90 kcal/mol. Different functional groups attached to fullerenes, and their influence on E(a) values are discussed, as are all the possible proton transfers for nonfunctionalized fullerenes.