Electron Transfer at Oxide/Water Interfaces Induced by Ionizing Radiation

Abstract

International audienceThe 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

Actual questions raised by nanoparticle radiosensitization

“…Second, the "chemical" effect deals with interface reactions. It has been shown that water radiolysis at solid/water interfaces has a very different chemistry than in the bulk (Chelnokov et al, 2014;Schofield et al, 2016) and the NP should be studied as such. Third, now that radicals generation by NP has been assessed at a macroscopic scale, their spatiotemporal production should be investigated through simulations and experimental work, giving access to a nanodosimetry.…”

Facile Synthesis of Highly Efficient One-Dimensional Plasmonic Photocatalysts through Ag@Cu2O Core–Shell Heteronanowires

“…We used p-benzoquinone (PBQ) as ·O 2 -scavengers, [57][58][59][60][63][64][65] triethanolamine (TEOA) as h + scavengers, 61,62,65 and isopropanol (IPA) as ·OH scavengers. 63,66 These scavengers were added into the MO solution together with the 1D Ag@Cu 2 O core-shell hetero-nanowires before irradiation. As depicted in Figure 6, the complete inhibition of degradation of MO in the presence of TEOA suggests that photogenerated holes are the major reactive species for the photocatalytic degradation of MO.…”

A comparison of the radiosensitisation ability of 22 different element metal oxide nanoparticles using clinical megavoltage X-rays

“…Two previous studies have compared the behaviour of several metal oxides under gamma irradiation. Chelnokov et al (2014) measured yields of solvated electrons, relative to water, following radiolysis of concentrated metal oxide NP aqueous solutions in low oxygen conditions. Six of those NPs are in common with our study: Al 2 O 3 , SiO 2 , ZnO, Nd 2 O 3 , Sm 2 O 3 , and Er 2 O 3 (Chelnokov et al 2014).…”

“…Petrik et al (2001) compared hydrogen production from adsorbed water on a wide range of 28 different element metal oxide powders (Petrik et al 2001). Chelnokov et al (2014) compared solvated electron production from six different element NPs (Chelnokov et al 2014).…”