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Greenhouse gas anthropogenic emissions have triggered global warming with increasingly alarming consequences, motivating the development of carbon-free energy systems. Hydrogen is proposed as an environmentally benign energy vector to implement this strategy, but safe and efficient large-scale hydrogen storage technologies are still lacking to develop a competitive Hydrogen economy. LOHC (Liquid Organic Hydrogen Carrier) improves the storage and handling of hydrogen by covalently binding it to a liquid organic framework through catalytic exothermic hydrogenation and endothermic dehydrogenation reactions. LOHCs are oil-like materials that are compatible with the current oil and gas infrastructures. Nevertheless, their high dehydrogenation enthalpy, platinoid-based catalysts, and thermal stability are bottlenecks to the emergence of this technology. In this review, hydrogen storage technologies and in particular LOHC are presented. Moreover, potential reactivities to design innovative LOHC are discussed.

Greenhouse gas anthropogenic emissions have triggered global warming with increasingly alarming consequences, motivating the development of carbon-free energy systems. Hydrogen is proposed as an environmentally benign energy vector to implement this strategy, but safe and efficient large-scale hydrogen storage technologies are still lacking to develop a competitive Hydrogen economy. LOHC (Liquid Organic Hydrogen Carrier) improves the storage and handling of hydrogen by covalently binding it to a liquid organic framework through catalytic exothermic hydrogenation and endothermic dehydrogenation reactions. LOHCs are oil-like materials that are compatible with the current oil and gas infrastructures. Nevertheless, their high dehydrogenation enthalpy, platinoid-based catalysts, and thermal stability are bottlenecks to the emergence of this technology. In this review, hydrogen storage technologies and in particular LOHC are presented. Moreover, potential reactivities to design innovative LOHC are discussed. [ABSTRACT FROM AUTHOR]

We report on QuasiElastic Neutron Scattering (QENS) investigations of the dynamics of protons and water molecules confined in nanostructured perfluorinated sulfonic acid (PFSA) materials, namely a commercial Aquivion membrane and the perfluorooctane sulfonic acid (PFOS) surfactant. The former is used as electrolyte in low-temperature fuel cells, while the latter forms mesomorphous self-assembled phases in water. The dynamics was investigated as a function of the hydration level, in a wide time range by combining time-of-flight and backscattering incoherent QENS experiments. Analysis of the quasielastic broadening revealed for both systems the existence of localized translational diffusive motions, fast rotational motions and slow hopping of protons in the vicinity of the sulfonic charges. The characteristic times and diffusion coefficients have been found to exhibit a very similar behaviour in both membrane and surfactant structures. Our study provides a comprehensive picture of the proton motion mechanisms and the dynamics of confined water in model and real PFSA nanostructures.

Abstract: Zirconium Phosphate (ZrP) inside a composite membrane Nafion-ZrP was studied by combining wide angle X-ray diffraction (XRD) and high-resolution solid-state 31P Nuclear Magnetic Resonance (NMR) under magic angle spinning conditions (MAS). We have, at first, investigated the physical features of ZrP powders that were prepared ex situ under different conditions leading to either amorphous or crystalline α-ZrP. ZrP incorporated into Nafion® membranes (in situ ZrP) was then studied. Informations obtained from X-ray and NMR data clearly show that the in situ ZrP is not in a purely crystalline phase. The presence of broad peaks in the X-ray spectra proves that the compound inside the membrane is semi-crystalline. This result is confirmed by MAS 31P NMR since the NMR spectra of in situ ZrP and ex situ semi-crystalline ZrP powder are alike. Moreover, the NMR analyses demonstrate that the phosphate groups can be found in three different connectivities with phosphorous atoms surrounded by either 2, 3 or 4 O, with predominantly 3 Obeing favored. [Copyright &y& Elsevier]

Hybrid organic-inorganic approaches are used for the synthesis of bifunctional proton exchange membrane fuel cell (PEMFC) membranes owing to their ability to combine the properties of a functionalized inorganic network and an organic thermostable polymer. We report the synthesis of both sulfonic and phosphonic acid functionalized mesostructured silica networks into a poly(vinylidenefluoride-co-hexafluoropropylene) (poly(VDF-co-HFP) copolymer. These membranes, containing different amounts of phosphonic acid and sulfonic acid groups, have been characterized using FTIR and NMR spectroscopy, SA-XRD, SAXS, and electrochemical techniques. The proton conductivity of the bifunctional hybrid membranes depends strongly on hydration, increasing by two orders of magnitude over the relative humidity (RH) range of 20 to 100%, up to a maximum of 0.031 S cm(-1) at 60 °C and 100% RH. This value is interesting as only half of the membrane conducts protons. This approach allows the synthesis of a porous SiO(2) network with two different functions, having -SO(3)H and -PO(3)H(2) embedded in a thermostable polymer matrix., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)