Effect of interfacial state in bipolar membrane on rectification and watersplitting

The effect of polymer component and structure in the membrane interface on rectification and water splitting is discussed in order to examine the wate r splitting mechanism. Various types of bipolar membranes which had differe nt amino groups in the anion exchange layer, different polyelectrolytes in the membrane interface, and different interface thickness of polystyrene we re prepared. The current-voltage characteristics and membrane resistance we re measured. If the space between the cation and anion exchange layers was produced, the Water splitting effect was reduced. Water splitting effect wa s accelerated even if a quaternary amino group Was inserted in the interfac e region instead of a secondary of ternary amino group, which implied that the water dissociation occurred not only due to the catalytic effect of the secondary or ternary amino group but also to the electric field, It was ev idenced that the membrane which had a thick interface region showed a high conductivity before the critical point of thickness of the interface region , which meant an increase in the reactive region of the water. It was prove d that if the anion exchange layer was composed of only binary or ternary a mino groups, the water splitting effect was also reduced due to the low ani on selectivity. (C) 1999 Elsevier Science B.V. All rights reserved.