The ionic resistance of membrane–electrode assemblies of oxygen–hydrogen fuel cell electrodes containing platinum nanoparticles on carbon black, carbon nanofibers, and proton-conducting Nafion polymer in a wide range of compositions (10–80 wt %) are studied in situ by the methods of current–voltage characteristics, electrochemical impedance spectroscopy, and simulation of the impedance hodograph. Conditions that make it possible to correctly determine the ionic resistance of the electrode on the basis of an analysis of the linear approximation of the high-frequency region of the impedance hodograph are found. It is shown that the occurrence of inhomogeneities and an anomalous increase in the ionic resistance with an increase in the content of Nafion in the electrode are associated with a decrease in the volume fraction of water-generation centers (particles of electrochemically active platinum), which leads to incomplete wetting of Nafion.

The article discusses platinum-carbon electrodes with mixed conductivity as part of membrane-electrode assemblies of fuel cells containing structural-modifying additives with structural elements of various types: carbon nanotubes with elongated structural elements and graphene-like materials with almost two-dimensional planes. Based on the data on the limiting current density obtained in potentiodynamic and potentiostatic modes, the mass transport losses of molecular oxygen transfer in these electrodes are investigated. Using different measurement conditions, the baric dependences of the current density were constructed, the limiting factors and mechanisms of oxygen transfer in the studied structures and the role of the introduced modifiers were clarified.

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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.

The structural and electrical characteristics of composite electrodes structurally modified due to the introduction of carbon nanofibers with high porosity and a fraction of transport pores and the formation of the Nafion proton-conducting polymer mainly in island form are studied. The analysis of energy losses for various compositions and optimization of the cathode composition are carried out. The efficiency of the cathode process was increased and the cathode characteristics were improved, the following characteristics of the membrane-electrode assemblies were achieved: at an electrical efficiency of ~ 0.5, the specific loading of platinum was 0.1 g / kW, and the maximum power density was 1 W / cm2.