Effects of inorganic substances on water splitting in ion-exchange membranes; I. Electrochemical characteristics of ion-exchange membranes coated with iron hydroxide/oxide and silica sol.

The effects of inorganic substances on water splitting in ion-exchange membranes (IEMs) were investigated. In this study, iron hydroxide/ oxide and silica sol were immobilized on the surface of the IEMs. The water-splitting capabilities of the metal-embedded cation-exchange membranes were 10(4)-10(5) times greater than those of the virgin membranes at the same current density. Similarly, silica sol (i.e., triple bond Si-OH groups) deposited on the anion-exchange membrane surface also drastically increased the proton transport numbers. It was thought that the bipolar structure consisting of H- and OH-affinity groups immobilized on the IEM surface increased water-splitting due to the enhancement of water polarization with the help of strong electric fields. This study revealed that metal oxides or silica groups (triple bond Si-OH), as well as metal hydroxides, can be used as catalysts for water splitting.