posted on 2018-09-06, 00:00authored byEugenio Vitale, Giuseppe Zollo, Lorenzo Agosta, Fabrizio Gala, Erik G. Brandt, Alexander Lyubartsev
Dissociative
and molecular water adsorption on the anatase (001)
surface is studied in the context of state-of-the-art density functional
theory in large supercells suited for adsorption studies at various
water coverage ratios. At low coverage values below 1/4 ML, water
adsorption remains dissociative and a network of hydrogen bonds between
the so formed hydroxyl groups favors the formation of a ridge surface
structure. The hydroxyl patterned (4 × 4) surface thus undergoes
a (2 × 4) reconstruction that causes the relief of the large
tensile stress measured in the unreconstructed surface along the direction
orthogonal to the ridge. This phenomenology is accompanied by the
loss of reactivity of the reconstructed surface with respect to the
dissociative water adsorption that becomes molecular above 1/4 ML.
We also show that the molecular adsorption on the terrace is weaker
than the one on the ridge. The present water reconstruction model
is discussed and compared to the well-known ADM model of the reconstructed
anatase (001) surface in dry environment.