Electron Transfer at Oxide/Water Interfaces Induced by Ionizing Radiation

Abstract

The electron transfer from oxide into water is studied in nanoparticle suspensions of various oxides (SiO₂, ZnO, Al₂O₃, Nd₂O₃, Sm₂O₃, and Er₂O₃) by means of pulse and γ radiolysis. The time-resolved and steady-state investigations of the present study demonstrate independently that whatever the band gap and the electron affinity of the oxide, the electron transfer always takes place in these nanometric systems: Irradiation generates hot electrons which have enough energy to cross the semiconductor–liquid interface. Moreover, picosecond measurements evidence that the spectrum of the solvated electron is the same as in water. Lastly, the decay of the solvated electron is similar on the picosecond to nanosecond time scale in water and in these suspensions, but it is clearly different on the nanosecond to microsecond time scale