  Water dissociation is a rate limiting step in many industrially important
chemical reactions. In this investigation, climbing image nudged elastic band
(CINEB) method, within the framework of density functional theory, is used to
report the activation energies (E a ) of water dissociation on Cu(111) surface
with a vacancy. Introduction of vacancy results in a reduced coordination of
the dissociated products, which facilitates their availability for reactions
that involve water dissociation as an intermediate step. Activation energy for
dissociation of water reduces by nearly 0.2 eV on Cu(111) surface with vacancy,
in comparison with that of pristine Cu(111) surface. We also find that surface
modification of the Cu upper surface is one of the possible pathways to
dissociate water when the vacancy is introduced. Activation energy, and the
minimum energy path (MEP) leading to the transition state remain same for
various product configurations. CINEB corresponding to hydrogen gas evolution
is also performed which shows that it is a two step process involving water
dissociation. We conclude that the introduction of vacancy facilitates the
water dissociation reaction, by reducing the activation energy by about 20%.
