Formation of the organic-inorganic proton exchange membrane

Abstract

The use of electrolyzers for the low-temperature water electrolysis with the solid polymer membrane is perspective for production of hydrogen using renewable energy sources. However, the high cost of membrane materials obstructs the mass commissioning of such electrolyzers. Most of the researches devoted to the technologies of membranes formation, alternative to Nafion®, deal only with organic materials. Aim: The aim of this research is to develop the method for formation of the competitive proton exchange membrane based on polyvinyl alcohol (PVA) and inorganic hydrates. Materials and Methods: The hydrated oxide of tin was added to the 2...10 % PVA solution, mixed and applied to inert base layer by layer for formation of the membrane. Then the membrane was separated from the base. The reinforcing mesh was used to improve mechanical properties of the membrane. The hydrated tin oxide was prepared by reaction of tin chloride and ammonium hydroxide solutions. Results: The conditions of formation of proton-exchange membranes based on polyvinyl alcohol and hydrated oxide of tin were investigated. The series of membranes containing 30, 50, 70, 80 and 90 % of hydrated tin oxide are obtained. It is shown that a solid membrane film with the thickness over 100 μm can be obtained if the content of PVA exceeds 30 %. It is shown that it is necessary to crosslink the chains of PVA in the resulting film. The structure of the obtained proton exchange membrane consists of PVA chains crosslinked by aldehyde, between which the globules of hydrated tin oxide are situated. The membrane conductivity is provided by both proton mobility of hydroxyl group of PVA and H₃O⁺/H₂O and OH^-/H₂O groups that are formed due to the partial dissociation of hydrated oxide on the surface of the globules.