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The deterioration of the environmental situation has led to the need to restructure the world’s power industry, and clean renewable power sources are coming to the forefront. This review deals with recent advances in the development of promising ion-exchange membrane materials for two types of application that have been intensely developing recently, namely, hydrogen energy and reverse electrodialysis. Special attention is paid to the comparison of two properties of membranes, conductivity and selectivity, that are competing but fundamentally important in both areas. Perfluorinated sulfonic acid membranes now play a dominant role in hydrogen power engineering, as they provide not only high proton conductivity but also chemical stability and low gas permeability. The review also covers other types of membrane materials, including anion exchange membranes, polybenzimidazoles and hybrid membranes containing inorganic nanoparticles that have been actively developed in recent years. The milder operating conditions of membranes in reverse electrodialysis units allow one to use less expensive non-perfluorinated membranes, including grafted ones. It is of note that in devices of this type, the selectivity of membranes to the transfer of oppositely charged ions is a more important parameter.

In this work, a comparative study was carried out of the transport properties and performance in a hydrogen-air fuel cell of the membranes based on polymethylpentene (PMP) with grafted sulfonated polystyrene and the standard Nafion® 212 membrane. Grafted cation-exchange membranes (GCM) were obtained by radiation graft post-polymerization of styrene onto UV-exposed PMP film followed by sulfonation with chlorosulfonic acid. The proton-conductivity of the GCM membrane with an ion-exchange capacity of 2.9 ± 0.1 meq/g reaches 21 ± 1 mS cm−1 at room temperature and 95% relative humidity, which is twice higher the conductivity of the Nafion® under the same conditions. The GCM-1 H2-permeability of 2.06∙10−7 cm2 s−1 even slightly lower than that of the Nafion® 212 (2.14∙10−7 cm2 s−1). A comparison of these membranes in the membrane electrode assemblies (MEA) of hydrogen-air fuel cells (FC) shows that the use of the grafted membranes with the high ion-exchange capacity is highly promising. The maximum performance of FC with grafted and Nafion® 212 membrane are both close to 180 mW/cm2 at the current density of 400 mA/cm2. At the same time, the high degree of crosslinking of sulfonated polystyrene leads to a decrease in conductivity and does not give an advantage in gas permeability.

The binding between the enzyme lactate dehydrogenase (LDH) and ferrihydrite nanoparticles (Fh-NPs) was investigated by means of small-angle neutron scattering (SANS), Fourier-transform infrared (FTIR) spectroscopy, fluorescence and Forster resonance energy transfer (FRET) and molecular docking. Fh-NPs - LDH compounds of dimensions under 100 nm are formed. The conformational changes and the mechanism of interaction between LDH and Fh-NPs simple and doped with Cu and Co, and the effect of these NPs on the thermal denaturation of LDH were monitored. The quenching mechanism is static, the binding occurring with moderate affinity, being mainly driven by hydrogen bonding and van der Waals forces. FRET occurs at a minimal distance of 2.55 nm. Thermal denaturation of LDH in the presence of simple and doped Fh-NPs shows that the thermodynamic parameters of protein unfolding are significantly changed with temperature. The denaturation temperature of LDH shifts to higher values in the presence of all Fh-NPs, than in the case of simple LDH. The docking approach estimates the energy corresponding to the best fit of the ferrihydrite in the LDH binding site near Trp. These results have direct implications on the uses of the complex of LDH with Fh-NPs in various biochemical, biological, or clinical applications.

The possibility of paraffins and C4 olefins mixture separation on membranes made of polyethylene with radiation-grafted sulfonated polystyrene is shown. The selective separation is achieved due to the butenes and isobutene facilitated transfer in the form of a π-complex with a proton. Moreover, despite the significantly larger cross-sectional size, obstructing the transfer, isobutene molecules are also transferred much faster than butane, and the separation coefficient reaches 3.8. An unusual fact was discovered of separation selectivity and permeability increase with the separated gases flow humidity rise.

A cathode nanomaterial LiFe0.8Mg0.2PO4 with olivine structure was synthesized by the sol-gel method and studied using X-ray diffraction analysis, scanning electron microscopy, Mossbauer spectroscopy and electrochemical testing under the operating conditions of a lithium-ion battery. It is demonstrated that the iron substitution with magnesium occurs in the studied material. Discharge capacity of LiFe0.8Mg0.2PO4/С is 127 mAh g−1 at a current of 20 mA g−1 and is close to the theoretical value for the considered composition. It is determined utilizing Mossbauer spectroscopy that at the early stage of the LiFe0.8Mg0.2PO4 charging process nanoscale regions are formed, having a FePO4 structure and an enhanced solubility of divalent iron ions.

The effect of ultrasonic treatment of iron oxide and iron oxyhydroxide nanoparticles (ferrihydrite nanoparticles synthesized by Klebsiella oxytoca microorganisms, ferrihydrite nanoparticles synthesized by a chemical method and hematite nanoparticles) is studied. Samples of nanoparticles were investigated using transmission electron microscopy, Mossbauer spectroscopy and X-ray diffraction methods. The formation of the α-Fe metal phase from nanoparticles of iron oxides and iron oxyhydroxides was detected. The metal phase is formed as a result of the reduction of iron ions during cavitation treatment. According to the experimental results, the presence of a protein or a polysaccharide component is necessary for the course of this reaction.

Results of hydrogen production study in methanol steam reforming (MSR) process with the use of Ru0.5–Rh0.5 catalysts supported on different carbon materials: synthetic graphite-like material Sibunit, carbon black Ketjenblack EC600DJ, detonation nanodiamonds (DND) and ZrO2-based material with fluorite structure, doped with ceria, have been described. The samples have been tested in conventional flow reactor and membrane (MR) reactor, containing Pd-based membranes with different composition, thickness and surface architecture. It has been shown that the catalytic activity of the composites depends on the support nature. The Ru Rh/DND catalyst exhibits the highest activity, whereas Ru Rh/Ce0.1Zr0.9O2–δ is the most selective. The use of Pd Ag (23%) foil with the surface modified by palladium black showed great advantages comparing to the smooth dense membrane. The use of the MR with the Pd Ag membrane improves the MSR reaction and provides almost 50% increase in the hydrogen yield. The hydrogen produced with the use of the MR is ultra pure.

Hybrid membranes based on polybenzimidazole PBI-O-PhT (a polymer based on 3,3′,4,4′‑tetraaminodiphenyl oxide and 3,3‑bis(p‑carboxyphenyl)phthalide) were obtained by casting with silica particles with the surface modified by sulfonic groups. The morphology, thermal stability, proton conductivity under various conditions, and hydrogen permeability of the obtained membranes were investigated. It was shown that modification with small amounts of silica (2–5%) increases the conductivity and practically has no influence on the gas permeability of the hybrid membranes.

In this paper we show sharp lower bounds for norms of even homogeneous Fourier multipliers in L ( L p ( R d ; X ) ) for 1 p ∞ and for a UMD Banach space X in terms of the range of the corresponding symbol. For example, if the range contains a 1 , … , a N ∈ C , then the norm of the multiplier exceeds ‖ a 1 R 1 2 + ⋯ + a N R N 2 ‖ L ( L p ( R N ; X ) ) , where R n is the corresponding Riesz transform. We also provide sharp upper bounds of norms of Banuelos–Bogdan type multipliers in terms of the range of the functions involved. The main tools that we exploit are A -weak differential subordination of martingales and UMD p A constants, which are introduced here.

International audience; This paper addresses hybrid ion exchange membranes fabricated by the synthesis of amorphous zirconiumphosphate (dopant contents from 0.5 to 24 wt%) directly in the pore and channel system of heterogeneouscation-exchange membrane RALEX® CM (by in situ technique). The incorporation of zirconium phosphate nanoparticlesinto the membrane system of pores and channels leads to the displacement of the pore water. As aresult, the cation transport numbers increase. The hybrid materials thus obtained are characterized by increasedionic resistance and enhanced monovalent ion selectivity. The former effect was eliminated by fabrication of asurface-modified membrane. The relative simplicity of modification, together with the benefits of the hybridmaterials make them promising for some membrane processes. Using 31P MAS NMR and elemental analysis,considerable difference between the zirconium phosphate composition inside and outside the membrane wasfound.

Nafion-117 membranes in the Na+-forms with pore-intercalated mixtures of aprotic organic solvents have been obtained. Dependences of solvent uptake of the membranes versus their pretreatment conditions and compositions of initial organic solvent mixtures are described. Ionic conductivity of the obtained membranes in the temperature range −20–50 °С is investigated using impedance spectroscopy. It is demonstrated that ionic conductivity increases with increasing solvent uptake. The highest conductivities at 30 °С (~4 mS/cm) are obtained for the membranes thermally treated in methanol and aged in ethylene carbonate-dimethylacetamide, ethylene carbonate-diethyl carbonate-dimethylacetamide and propylene carbonate-dimethylacetamide-tetrahydrofuran mixtures. Thermal stability is studied by differential scanning calorimetry. It is shown that the membrane with intercalated propylene carbonate-dimethylacetamide-tetrahydrofuran mixture is characterized by a constant phase composition in a broad temperature range (up to −100 °С) and retention of high conductivity at low temperatures (~1 mS/cm at −20 °С).

The process of oxidative dehydrogenation of ethane (ODE) was carried out in a catalytic membrane reactor-distributor on a Mo-V-Te-Ox catalyst supported on asymmetric ceramic membranes. The obtained results show the obvious advantages of ODE with the use of a membrane system. Application of the membrane approach allows us to use initial gas mixtures with the O2:C2H6 ratios that are unacceptable for safety reasons in conventional reactors. Under optimal process conditions, the conversion of ethane of 70% can be achieved in a membrane reactor while maintaining the ethylene selectivity in the range of 95–98%.

The possibility of ethane/ethylene mixture separation at the passing these gases through polyethylene-graft-sulfonated polystyrene membranes in silver and hydrogen forms has been shown. The results showed that the permeability of ethylene and the value of the separation coefficient increased significantly with increasing relative humidity of the separated gases. It was concluded that in both cases the transfer of ethylene occured in the form of a positively charged complex. The patterns of change in the permeability and separation factor were explained on the basis of the structure of the initial membranes and the solubility of the separated gases in the “phases” forming the membrane.

Samples of synthetic ferrihydrite with an average nanoparticle size of 2.7 nm have been examined by magnetometry and Mossbauer spectroscopy. Ferrihydrite is characterized by the antiferromagnetic interactions between the magnetic moments of iron atoms. In ferrihydrite nanoparticles, as in any other antiferromagnetic ones, structural defects induce the formation of an uncompensated magnetic moment, which determines the magnetic properties typical of single-domain ferro- and ferrimagnetic particles. The manifestation of the magnetic interactions between ferrihydrite nanoparticles in the magnetic properties of the material and in the temperature evolution of Mossbauer spectra has been in focus. The results obtained on synthetic ferrihydrite have been compared with the data for the biogenic ferrihydrite sample with a similar average size of particles surrounded by a polysaccharide shell, which weakens and screens the interparticle magnetic interactions. A clear manifestation of the effect of the interparticle magnetic interactions on the transition to the blocked state is the presence of a significant contribution of the relaxation component in the Mossbauer spectra at temperatures of the transition from the superparamagnetic to blocked state. The temperature dependence of the particle relaxation time obtained from the Mossbauer spectra points out the collective effect of freezing of the magnetic moments of particles due to the magnetic interactions between them.

Iron doped lithium titanates Li4+z-3yTi5-zFez+yO12 (0 ≤ z + y ≤ 0.3) have been synthesized and characterized by X-ray diffraction, scanning and transmission electron microscopy, 57Fe Mossbauer spectroscopy, and cyclic voltammetry. Their performance as anode materials for lithium-ion batteries was studied in a wide potential range (0.01 − 3 V). Rietveld refinements and 57Fe Mossbauer spectroscopy data show that iron cations occupy both tetrahedral 8a and octahedral 16d sites in the spinel structure. At that, iron occupancy of the octahedral sites is approximately twice as much as the occupancy of the tetrahedral ones. Occupancy of octahedral sites by Fe3+ ions increases after cycling. Li4+z-3yTi5-zFez+yO12 (z + y = 0.2) exhibits higher electrochemical capacity at high current densities than the pristine Li4Ti5O12. Moreover, capacity of doped material increases after cycling at high current densities.