posted on 2020-06-04, 18:40authored byEnric Petrus, Mireia Segado, Nuno A. G. Bandeira, Carles Bo
We present a density
functional theory study for the photochemical water oxidation reaction
promoted by uranyl nitrate upon sunlight radiation. First, we explored
the most stable uranyl complex in the absence of light. The reaction
in a dark environmen proceeds through the condensation of uranyl monomers
to form dimeric hydroxo-bridged species, which is the first step toward
a hydrogen evolution reaction (HER). We found a triplet-state-driven
mechanism that leads to the formation of uranyl peroxide and hydrogen
gas. To describe in detail this reaction path, we characterized the
singlet and triplet low-lying states of the dimeric hydroxo-bridged
species, including minima, transition states, minimal energy crossing
points, and adiabatic energies. Our computational results provide
mechanistic insights that are in good agreement with the experimental
data available.