Synthesis and prediction of transport properties of hybrid bilayer ion-exchange membranes

Bilayer membranes consisting of a thick layer of a pure perfluorinated membrane MF-4SC and a thinner layer of the same membrane modified by halloysite nanotubes (HNTs), functionalized with platinum nanoparticles, are investigated. Membrane synthesis was carried out by casting from a polymer solution followed by drying. One of the samples revealed a weak asymmetry of diffusion permeability and the current–voltage characteristic. By using the physicochemical characteristics of monolayer membranes obtained earlier, the dependence of the diffusion permeability of the bilayer composite on the electrolyte concentration is described with satisfactory accuracy. The numbers of water transport and the selectivity of hybrid membranes, and their power characteristics in the membrane–electrode block of the fuel cell, were studied. The introduction of halloysite leads to a decrease in both parameters, and the subsequent addition of platinum compensates for the negative effect of halloysite addition: the maximum specific power becomes higher than that for the original/pure membrane, and the range of operating current densities widens. This makes it possible to predict the effective use of hybrid membranes based on MF-4SC and HNTs with platinum nanoparticles, not only as separating diaphragms in fuel cells and electromembrane devices, but also as promising catalytic systems.