Charge transfer across the Cr2O3, Fe2O3, and ZrO2 oxide/water interface: A pulse radiolysis study

Abstract

The transfer of electrons across the oxide/water interface has been investigated for oxide particles which are typically found incorporated into structural material surfaces within water circuits of nuclear systems. A pulse radiolysis study was conducted in order to observe the generation and decay kinetics of hydrated electrons in water in the presence of metal oxides. The presence of the oxides was found to have an effect on hydrated electron decay behaviour, with Fe2O3 retarding the decay rate and ZrO2 increasing the decay rate. The presence of Cr2O3 appeared to have negligible effect on the decay rate. The electron yield after the irradiation pulse was found to increase for all oxide/water mixtures relative to neat water, indicating electron transfer from the oxide to the water. The responses were attributed to electronic properties such as the band gap of the materials with respect to redox reactions at the material surface, as well as the effect of hydroxyl radicals on electron behaviour in the presence of the oxides.