Proton-exchange membranes are crucial for water electrolyzers and fuel cells, but their performance declines under low humidity due to dehydration. Existing reviews mainly list experimental results without analyzing the mechanisms of proton conductivity stabilization. This review systematically summarizes approaches to enhance moisture-independent proton conductivity and evaluates their prospects. Key factors governing conductivity include microstructure, sulfonic group concentration, and hydration level. Stability under dry conditions depends on water retention and thermal resistance. Main strategies involve hybrid composite membranes, ionomer structure control via pre-treatments, and novel proton-conducting polymers. Promising directions include oriented channel structures, MOFs, and graphene-based materials. The stabilization mechanism relies on retaining water through hydrophilic additives that form stable hydrates, enabling proton transport even under harsh conditions (up to 120 °C and 50% RH, per US DOE targets). Among Nafion alternatives, sulfonated aromatic polymers and phosphoric-acid-doped polybenzimidazole demonstrate good performance at elevated temperatures (100-200 °C), though durability remains a challenge for the latter. Despite ongoing research, Nafion-based composites still offer one of the best overall balances of conductivity, stability, and processability. A significant research gap persists: long-term membrane performance is poorly studied, and many additives degrade over time or block proton transport sites due to ion exchange with metal cations.

Stability and durability of electrochemical energy conversion systems are significant issues. In this study, two stabilization strategies were investigated: 1) the application of few-layer graphene as a barrier layer on both sides of the Nafion membrane, and 2) the incorporation of polytetrafluoroethylene directly into the catalyst layers. Electrochemical performance was assessed in a two-electrode configuration: potentiostatic aging at 2.5 V and hydrogen crossover measurements. The characterization of materials functioning as barrier layers was conducted using scanning and transmission electron microscopy, laser correlation spectroscopy, and differential thermal analysis. It is shown that both components stabilize Nafion through interfacial interactions, resulting in a longer service life and reduced hydrogen crossover. While the reference sample showed increased crossover, the modified samples exhibited reductions of 50% and 33%. These findings underscore the potential of the studied materials in enhancing the stability of polymer electrolyte membrane water electrolyzers, contributing to the advancement of more durable and efficient systems for hydrogen energy applications.

Abstract Graphene-reinforced proton exchange membranes (PEMs) offer a promising route to reduce fuel crossover while enhancing mechanical strength, chemical durability, and thermal stability in electrochemical energy systems such as fuel cells and water electrolyzers. Achieving these improvements requires graphene with controlled thickness, low defect density, and minimal oxygen content, yet the scalable production of such materials remains a challenge. Two scalable deposition techniques, electrophoretic coating (e-coating) and spray-coating, were systematically evaluated for coating formation. Comparative analysis using UV-Vis spectroscopy indicated that e-coating may induce slight membrane degradation, whereas spray-coating preserves the native polymer structure. Scanning electron microscopy confirmed the formation of uniform, submicron coatings. The graphene e-coating demonstrated the highest barrier efficacy, lowering the crossover current density to 0.9 mA/cm², a substantial improvement over the 6 mA/cm² observed for the uncoated membrane. The spray-coated sample exhibited a crossover current density of 1.3 mA/cm². Furthermore, the e-coated membrane showed superior barrier properties and lower proton resistance at elevated temperatures (>60 °C) compared to the spray-coated counterpart. The peak short-circuit current densities were attained at 40-50 °C. These findings establish e-coating as an effective method for fabricating high-performance graphene-based barrier layers on PEMs, enabling reduced crossover and extended operational lifetime.

We report on hydrothermal synthesis and structural characterization of Li-Fe-montmorillonite (MMT). To date, this 2:1 type phyllosilicate attracts attention due to such properties as high ion mobility, hydrophilicity, electrical and thermal resistance. Due to that, various MMTs may serve as perspective components of Li-ion batteries (electrolyte and separator fillers, as well as protective buffer layer on top of Li metal anode). Scarce data on synthetic Li-Fe3+-MMTs motivated us to investigate formation process and structure features of such phyllosilicate by X-ray diffraction, UV-visible and Mossbauer spectroscopy, and other methods. We established critical Fe(3+ )content and temperature range needed for almost single-phase MMTs formation. Around 20 % of total Fe may occupy tetrahedral site of MMT layer. Thermal behavior of Li-Fe-MMT strongly depends on hydrothermal synthesis conditions because of different Li+ amount present in the interlayer space and in the layer vacancies.

This work presents a comparative study of graphene exfoliation technologies from various graphite precursors—spectral graphite and thermally expanded graphite (Graflex)—using ultrasonic treatment and electrochemical methods in the presence of the ionic surfactant Nafion. The influence of exfoliation parameters, the nature of the starting material, and the presence of surfactant additives on the morphology, dispersibility, stability, and structural characteristics of the resulting graphene-containing dispersions was investigated. Particular attention is paid to a two-step technology combining pulsed electrochemical exfoliation with subsequent mild ultrasonic treatment. Comprehensive characterization of the samples was carried out using UV–Vis spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), electron microscopy, electron diffraction (ED), dynamic light scattering (DLS), and X-ray photoelectron spectroscopy (XPS). It was found that the use of Nafion significantly enhances exfoliation efficiency and contributes to the stabilization of the dispersions. Graphene sheets obtained from Graflex exhibit significantly larger lateral dimensions (up to 1 μm or more) compared to those exfoliated from spectral graphite (100–300 nm). The approach combining the use of Graflex and pulsed electrochemical exfoliation in the presence of Nafion with subsequent low-power ultrasonic treatment enables the production of few-layer graphene (1–3 layers) with high stability.

inorganic-polymer composites are widely used as radio-absorbing materials, the study of their properties is important from the point of view of improving technical characteristics. The results of the study of Nafion/thermoexpanded graphite and Nafion/carbon black composites by nuclear magnetic resonance and thermogravimetry are presented. The formation of new compounds at the contact boundaries of the components, leading to thermal stabilization of the composites, is shown. Differences between thermally expanded graphite and carbon black upon interaction with Nafion are discussed.

A technology for obtaining graphene by means of ultrasonic dispersion of thermally expanded graphite in the presence of a surface-active polymer Nafion is presented. The technology makes it possible to obtain large amounts of low-layer (1-3 layers) graphene in a relatively short time. An approach to control the dispersion process based on UV spectroscopy of dispersions is described. A mechanism is proposed for the effect of a surface-active polymer on the production of low-layer graphene by ultrasonic dispersion. Keywords: graphene, ultrasonic dispersion, thermally expanded graphite.

Ensuring the stable operation of proton exchange membrane fuel cells is conducive to their real-world application. A promising direction for stabilizing electrodes is the stabilization of the ionomer via the formation of surface compounds with graphene. A comprehensive study of the (electrochemical, chemical, and thermal) stability of composites for fuel cell electrodes containing a modifying additive of few-layer graphene was carried out. Electrochemical stability was studied by cycling the potential on a disk electrode for 5000 cycles. Chemical stability was assessed via the resistance of the composites to H2O2 treatment using ion-selective potentiometry. Thermal stability was studied using differential thermal analysis. Composites were characterized by UV-Vis spectroscopy, Raman spectroscopy, EDX, and SEM. It was shown that graphene inhibits Nafion degradation when exposed to heat. Contrariwise, Nafion is corrosive to graphene. During electrochemical and chemical exposure, the determining change for carbon-rich composites is the carbon loss (oxidation) of the carbon material. In the case of carbon-poor composites, the removal of fluorine and sulfur from the Nafion polymer with their partial replacement by oxygen prevails. In all cases, the F/S ratio is stable. The dispersity of Nafion in a sample affects its chemical stability more than the G/Nafion ratio does.

The stability of new membrane–electrode assemblies of a proton-exchange membrane fuel cell with highly porous electrodes and low Pt loading, based on the proton-conducting polymer Nafion, was characterized in conditions of electrochemical aging. A comprehensive study of the effect of the microstructure on the evolution of the electrochemical characteristics of the new assemblies was obtained by voltammetry, electrochemical impedance spectroscopy, X-ray powder diffraction, and scanning electron microscopy. Because high (>70%) porosity provides intensive mass transfer inside an electrode, structural-modifying additives—long carbon nanotubes—were introduced into the new electrodes. PEM fuel cells with electrodes of a conventional composition without carbon nanotubes were used for comparison. The aging of the samples was carried out according to the standard accelerated method in accordance with the DOE (Department of Energy) protocols. The results show two fundamental differences between the degradation of highly porous electrodes and traditional ones: 1. in highly porous electrodes, the size of Pt nanoparticles increases to a lesser extent due to recrystallization; 2. a more intense “washout” of Nafion and an increase in ionic resistance occur in highly porous electrodes. Mechanisms of the evolution of the characteristics of structurally modified electrodes under electrochemical aging are proposed.

Inorganic-polymer composites are widely used as radio-absorbing materials, the study of their properties is important from the point of view of improving technical characteristics. The results of the study of Nafion/thermoexpanded graphite and Nafion/carbon black composites by nuclear magnetic resonance and thermogravimetry are presented. The formation of new compounds at the contact boundaries of the components, leading to thermal stabilization of the composites, is shown. Differences between thermally expanded graphite and carbon black upon interaction with Nafion are discussed.

Thermal degradation of multiwalled carbon nanotubes, thermally expanded graphite, Nafion proton-conducting polymer, and binary composites based on it (Nafion + carbon nanotubes, Nafion + thermally expanded graphite) in air was studied. The temperature dependence of the lifetime of the materials was estimated. The structure of the materials studied was characterized by field emission scanning and transmission electron microscopy, thermal gravimetric analysis, and differential scanning calorimetry. The degradation kinetics was examined using nonisothermal kinetic analysis; the activation energy and pre-exponential factor of the Arrhenius equation were determined. The thermal stability of Nafion in its binary composites with carbon materials is enhanced owing to the formation of surface compounds on the Nafion–carbon interface. The degree of stabilization, or the composite lifetime, depends on the component composition of the composite and on the structure of the nanocarbon material. The largest effect was reached when using a composite with thermally expanded graphite at the component weight ratio of 1 : 4. Its lifetime at 80°C was 1014.4 min, exceeding by 4 orders of magnitude the lifetime of straight Nafion (1010.4 min). In the case of the composite with thermally expanded graphite at the component weight ratio of 1 : 4, Nafion polymer is distributed over the surface of the carbon material to a greater extent compared to the other compositions because the better surface accessibility. Introduction of carbon and carbon–polymer composites with mixed conductivity in the course of fabrication of electrochemical electrodes enhances their heat resistance and limiting operation temperature, thus allowing the operation life to be prolonged and production cost of the items to be reduced.

The electrochemical characteristics of a carbon carrier play an important role in catalyst investigations. The evolution of the electrochemical characteristics of Vulcan XC-72 carbon black and a glassy carbon disk electrode was studied under prolonged electrochemical action. The electrochemical action was performed by repeated application of a sawtooth periodic potential to the electrodes in the range from 0.05 to 1 V vs. RHE and back at a scan rate of 50 mV/s. The EDL charging current, the cyclic current–voltage curves, the equilibrium electrode potential, and the dissolved oxygen reduction current in potentiostatic mode at 0.05 V vs. RHE were recorded periodically. Carbon black was characterized by helium pycnometry, SEM, TEM, X-ray diffraction, and Raman spectroscopy. The currents on the carbon black were several orders of magnitude higher than those on the glassy carbon. The differences in the dynamics of electrochemical characteristics are discussed.

Submicron spherical silica particles were synthesized via base hydrolysis of tetraethoxysilane (TEOS) and phenyltriethoxysilane (PTEOS) in a presence of cetyltrimethylammonium bromide. It was shown that the replacement of a part of TEOS with PTEOS in the reaction mixture led to formation of particles containing hierarchical micro-mesoporous structure with specific surface area of up to similar to 1170 m(2) g(-1). The amount of PTEOS leads to the increase of water contact angle of the particles from 10 degrees to 155 degrees which causes a gradual change in their surface properties from hydrophilic to superhydrophobic. The static adsorption capacity of the particles was measured for water, toluene and methyl isobutyl ketone and was found to be affected by both the amount of OH- or C6H5-groups on the surface and the characteristics of porosity. In particular, the adsorption capacity for non-polar volatile organics increases with the increase of the hydrophobicity of particles. It was found that synthesized superhydrophobic silica particles efficiently and quickly absorb oil from water surface and then can be easily removed mechanically.

The article presents the results of a study of inorganic-polymer nanocomposites Nafion/thermally expanded graphite and Nafion/carbon black by nuclear magnetic resonance and thermogravimetry. The struc-ture of carbon materials was characterized by electron microscopy and adsorption structural analysis by low -temperature nitrogen adsorption. The presence of the interaction of Nafion polymer and carbon material at the interface between the components leading to thermal stabilization of the composites is shown, and the differences between thermally expanded graphite and carbon black due to their morphology during interaction with Nafion are discussed.

Non‐centrosymmetric metal–organic frameworks (MOFs) have recently emerged as a promising class of coordination polymers for nonlinear optics and light conversion. Nevertheless, achieving high endurance and efficiency for the light conversion within the whole visible range by a single crystal of MOF remains a challenge. This article reports on the design of two non‐centrosymmetric MOFs based on a 1,3,5‐benzenetricarboxylic acid ligand and Er/Co ions, providing an efficient and simultaneous multiple second and third optical harmonic generations (SHG, THG) from 400 to 750 nm with a high endurance (over 100 cycles or 3 h of continuous operation). Optical experiments and quantum chemical modeling of the MOF single crystals confirm the polarization and chemistry‐dependent efficiency of SHG and THG, associated with the varied MOFs' symmetry and dipole moment. The observed coherent light conversion within the whole visible range by MOF single crystals at ambient conditions makes it possible to achieve the multicolor (up to three) coherent emission required for modern laser technologies, making MOFs highly competitive and sustainable materials for nonlinear optics.

Technology of obtaining graphene by means of ultrasonic dispersion of thermally expanded graphite in the presence of a surface-active polymer Nafion is presented. The technology makes it possible to obtain large amounts of low-layer (1-3 layers) graphene in a relatively short time. An approach to control the dispersion process based on UV spectroscopy of dispersions is described. A mechanism is proposed for the effect of a surface-active polymer on the production of low-layer graphene by ultrasonic dispersion.

We have tested platinum–carbon electrodes with mixed conductivity as parts of membrane electrode assemblies of fuel cells containing structure-modifying additives with different structural elements (carbon nanotubes with extended structural elements and graphene-like materials with nearly 2D planes). Mass-transport losses of molecular oxygen transfer in these electrodes have been investigated on the basis of data on the limiting current density obtained in the potentiodynamic and potentiostatic regimes. The pressure dependences of the current density have been plotted using various conditions of measurements. Limiting factors and oxygen transport mechanisms in the tested structures and the role of introduced modifiers have been determined.

By means of the disk-electrode method (stationary and rotating), regularities of changes in the mass-transport properties of composite electrodes containing platinum nanoparticles on carbon black, the addition of carbon material with different shapes of structural elements (three- and pseudo-one-dimensional carbon nanotubes with different length-to-diameter ratios), and the Nafion proton-conducting polymer were studied. The transport of molecular oxygen inside a porous electrode to the platinum surface has been studied. Mechanisms for changing the mass-transport properties of structurally modified electrodes during electrochemical action are proposed.

The variation of surface area of platinum–carbon material of hydrogen fuel cell electrodes in the presence of structure-modifying carbon nanotubes under long-term electrochemical action is studied. The method of cyclic voltammetric curves is used to study the specific features of the variation of platinum nanoparticle surface area by the hydrogen desorption in the hydrogen region and the charging current of electrical double layer in the double-layer potential region. The results are obtained separately for the electrodes on the cathodic and anodic sides.

Peculiarities of molecular oxygen transport in platinum–carbon electrodes exhibiting mixed conductivity and containing structure-modified admixtures with structural elements of various types (short and long carbon nanotubes with extended structural elements characterized by different length/diameter ratios and graphene-like materials with practically 2D planes) are studied by the methods of a rotating disk electrode.