Том 55, № 8 (2019)

Oxygen transport (including oxygen mobility and surface reactivity) is one of the important factors governing electrochemical activity of solid oxide fuel cells electrodes as well as oxygen and hydrogen separation membranes based on materials with mixed oxide-ionic and electronic conductivity. In this work, oxygen mobility data obtained for a series of materials destined for such devices using modern techniques of oxygen isotope heteroexchange are summarized. Series of solid oxide fuel cells’ and membranes’ materials were studied by isotope exchange of their oxygen with ¹⁸O₂ and C¹⁸O₂ in isothermal and temperature-programmed modes using closed and flow reactors and data analysis based on developed model of oxygen diffusion and exchange. For solid electrolytes’ materials (Sc- and Ce-doped zirconia) as well as for proton-conducting materials [Ln_5.5(Mo,W)O_11.25], the effect of composition heterogeneity on the oxygen mobility was demonstrated. For Ln_{6 – x}WO_12 – δ, a strong effect of structure on the oxygen mobility was demonstrated. For oxides with asymmetric structure, where oxygen migration proceeds via cooperative mechanisms [La₂(Mo,W)₂O₉, (Ln,Ca)₂NiO₄], the doping hampers the cooperative migration, resulting in oxygen mobility deterioration and sometimes forming additional slow diffusion channels. In the PrNi_0.5Co_0.5O₃–Ce_0.9Y_0.1O₂ nanocomposites that are materials of the solid oxide fuel cells’ cathode and functional layer of the oxygen separation membranes, two diffusion channels were observed, where more mobile oxygen corresponds to the fluorite phase and interfaces; less mobile, to the perovskite phase. This is due to special features of cations redistribution between the phases.

The effect of F^– and Cl^– doping on the transport properties of the proton conductor Ba₄In₂Zr₂O₁₁ was analyzed. The halogen-substituted phases were found to be capable of water intercalation and proton transfer. The introduction of halide ions in low concentrations led to an increase in oxygen-ion and proton conductivity.

The composites based on the oxygen-ion and proton conductor Ba₂In_1.7W_0.3O_5.45 with a 30 mol % Ba₂InNbO₆ addition were studied. The processing of the compact samples of the composite electrolyte at 1430°C gave ceramics with a density of 95%. The total electric conductivity of the composite in dry and humid atmospheres decreases by ~0.5 order of magnitude compared with the conductivity of the matrix.

This paper concentrates on the electrodeposition of CZTS kesterite thin films on ITO coated glass. The main objective of the article is to compare the electrodeposition from an ionic liquid electrolyte, which is choline–urea, and from an aqueous electrolyte, that is the citrate buffer solution. The electrochemical behaviour of the citrate buffer shown a remarkable evolution of the hydrogen, which was less in the choline chloride–urea electrolyte. The XRD pattern of the films provided from the two electrolytes confirms the presence of the kesterite form of Cu₂ZnSnS₄. The surface morphology of the samples was examined using scanning electron microscopy and showed that electrodeposition from the citrate buffer electrolyte leads to have CZTS thin films with less porous morphology.

Activated carbon Norit Supra DLS 30 and carbon fabrics L-03 and T-040 were studied as electrode materials for supercapacitors with aqueous sodium sulfate. The use of the T-040 fabric led to higher specific capacity than in the case of carbon tape L-03. The decrease in the capacity when cycling the capacitors with electrode materials of both fabrics was almost the same. The introduction of benzotriazole in the electrolyte or electrode material increased the operating voltage and specific characteristics of the supercapacitor.