jp6b08278_si_001.pdf (390.41 kB)
Adsorption, Dissociation, and Dehydrogenation of Water Monomer and Water Dimer on the Smallest 3D Aluminum Particle. The O–H Dissociation Barrier Disappears for the Dimer
journal contribution
posted on 2016-10-07, 00:00 authored by Jerzy MocWe present a detailed
mechanistic study on the interaction and
reaction of water monomer and water dimer with the smallest 3D aluminum
particle (Al6) by employing density functional and explicitly
correlated coupled cluster CCSD(T)-F12 theories. Water adsorption,
dissociation, and dehydrogenation are considered. For the monomer
reaction, where core–valence correlation and an extrapolation
to the complete basis set limit is allowed for, our coupled cluster
calculations predict the O–H dissociation barrier of about
2 kcal/mol. For the dimer reaction, two distinct reaction paths are
identified, initiated by forming separate dimer complexes wherein
(H2O)2 adsorbs mainly via the oxygen atom of
the donor H2O molecule. The key O–H dissociation
transition states of the dimer reaction involve a concerted migration
of two H atoms resulting in the dissociation of the donor molecule
and formation of the OH–water complex adsorbed on the metal
cluster’s surface. The most remarkable feature of both dimer
reaction energy profiles is the lack of the overall energy barrier
for the (rate-determining) O–H dissociation. The hydrogen bond
acceptor molecule is suggested to have an extra catalytic effect on
the O–H dissociation barrier of the hydrogen bond donor molecule
by removing this barrier. A similar effect on the dehydrogenation
step is indicated.