Synthesis, structure and properties of composite proton-conducting membranes based
on a Nafion-type perfluorinated copolymer with Zr$_{1-x}$Y$_x$O$_{2-0.5x}$ nanoparticles
Abstract:
Zr$_{1-x}$Y$_x$O$_{2-0.5x}$ nanoparticles were introduced into the sulfonic acid form of the Nafion-type perfluorinated copolymer prior to membrane formation to improve its water retention, thermal stability, and proton conductivity. Since the conditions under which nanoparticles are formed can significantly influence their size, phase composition, morphology, and surface chemistry, various approaches to filler synthesis were considered in this study. It was found that among the wet-chemical methods used to produce zirconia-based nanoparticles, solvothermal synthesis offers the most promise in terms of increasing the surface proton conductivity of composite membranes. This method ensures small size, large specific surface area, and high hydrophilicity of the nanoparticles. Consequently, their incorporation into a Nafion-type perfluorinated copoly- mer increases the membrane’s moisture retention and improves to its proton-conducting properties. In the case of Zr$_{1-x}$Y$_x$O$_{2-0.5x}$ nanoparticles formed under solution combustion conditions, their more hydrophobic surface did not contribute to an increase in the moisture content of the perfluorinated copolymer, but did allow its maximum operating temperature to be increased by 20$^\circ$C.
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