New insights into the interfacial interactions of O2 and H2O molecules with PuH2 (110) and (111) surfaces from first-principles calculations

The interfacial reaction of highly active plutonium hydride in humid circumstance is of great interest in nuclear safe handling and storage, but it is poorly understood so far. In this paper, we first studied the O-2 adsorption on (110) and (111) surfaces of PuH2 by firstprinciples DFT thorn U method. The results show that there are dissociative and nondissociative adsorption of oxygen on the surfaces. We analyze the vibrational frequencies of non-dissociative oxygen adsorbed on the surfaces. It is found that the corresponding frequency of oxygen with bond length of 1.330-1.340 angstrom is 1094.8-1098.2 cm(-1). The corresponding frequency of oxygen with bond length of 1.448-1.500 angstrom is 726.3 e905.2 cm(-1). It shows that non-dissociative oxygen could be considered as superoxide (O-2(-)) or peroxide (O-2(2-)) species. In order to expound the atomistic evolution process of oxidized surface exposed to moist air or corrosive solution, the interactions between H2O molecules and the strongest oxygen adsorption structures were further explored. The results indicate that H2O molecules could dissociate into OH groups and H atoms, then they were captured to create PueO and HeO bonds. This work could provide new insights into the adsorption morphology of oxygen on hydride surface and the interaction between oxide/hydride interface and water. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This paper investigates the adsorption of oxygen on plutonium hydride in humid conditions using first-principles DFT method, shedding light on the interactions between hydride, oxygen, and water.