Radiolysis of ZrO2 Surface Modified with Polyphenols

Abstract

The surface of ZrO2 was modified with various aromatic polyphenols to study their impact on the surface chemistry induced by γ radiolysis. Molecular hydrogen (H2) production in the radiolysis of water adsorbed on zirconium oxide (ZrO2) is enhanced over that observed in bulk water. Modified with catechol, ZrO2 demonstrated a decrease in the level of H2 generation under ionizing radiation. Suppression of H2 production can be explained by the radical-scavenging ability of the polyphenol ring, which likely scavenges generated H atoms, preventing their combination reactions. Additionally, catechol adsorption caused a decrease in the amount of free surface hydroxyl groups and surface water, which could also cause the suppression of H2 generation. Introducing additional substituents to catechol molecules caused a further decrease in H2 generation in radiolysis. Thus, modification of the surface of oxides with radical-scavenging organic ligands might be useful for H2 production control in nuclear waste and other environments where oxides and water are present under high radiation fields.