Effect of polymer composition in intermediate layer on water splitting in bipolar membranes

Abstract

The relationship between the water splitting effects and the chemical composition of the intermediate layer has been studied. Firstly, the membrane resistance decreases if a quaternary ammonium group or a carboxyl group is inserted in the intermediate layer instead of a secondary or tertiary amino group, which implies that the water dissociation occurs not only due to the catalytic effect of the secondary or tertiary amino group but also to the electrical field. Secondly, it is proved that the current efficiency is determined by the ion exchange capacity in the anion and cation exchange layers, but not by the chemical structure of intermediate layer. Thirdly, it is also evidenced that the membrane which has a thick intermediate layer showed a high conductivity before the critical point of thickness of the intermediate layer, which means an increase in the reactive region of the water. In this study, we could not find evidence that the chemical reaction model is superior.