Reaction mechanism between small-sized Ce clusters and water molecules II: an ab initio investigation on Cen (n = 1–3) + mH2O (m = 2–6)

Abstract

Possible reactions between the products of the three independent reactions involving a small Ce cluster and a single water molecule, Ce_n + H₂O (n = 1–3), and an additional H₂O molecule are systematically investigated. The ground-state isomers of the final products and the reaction pathways involving multiple water molecules are predicted. We find that under either ambient or UV-irradiation conditions, all the reactions can entail low energy barriers. In addition, the final products of the reaction between Ce_n and more than two H₂O molecules are also predicted through an extensive structural search. The calculated reaction energies suggest that although small-sized Ce clusters can react with more than two water molecules, the reactions with one or two water molecules are dominant. The electronic structures of all the ground-state isomers and the corresponding oxidation states of Ce atoms in these isomers are computed and determined via the natural bond orbital (NBO) method. The results indicate that a single Ce atom and a Ce₂ cluster can react with a maximum of four and six water molecules, respectively, while a Ce₃ cluster can react with more than six water molecules. This comprehensive study offers an improved understanding of the mechanism underlying the reactions between a single Ce atom or a small Ce cluster and two or more H₂O molecules. Knowledge obtained from this study can be helpful for the development of high-performance Ce-doped or Ce-based catalysts.