Vibrationally promoted dissociation of water on Ni(111).
Water dissociation on transition-metal catalysts is an important step in steam reforming and the water-gas shift reaction. To probe the effect of translational and vibrational activation on this important heterogeneous reaction, we performed state-resolved gas/surface reactivity measurements for the dissociative chemisorption of D2O on Ni(111), using molecular beam techniques. The reaction occurs via a direct pathway, because both the translational and vibrational energies promote the dissociation. The experimentally measured initial sticking probabilities were used to calibrate a first-principles potential energy surface based on density functional theory. Quantum dynamical calculations on the scaled potential energy surface reproduced the experimental results semiquantitatively. The larger increase of the dissociation probability by vibrational excitation than by translation per unit of energy is consistent with a late barrier along the O-D stretch reaction coordinate.
Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
P Morten
PM
Hundt
Bin
B
Jiang
Maarten E
ME
van Reijzen
Hua
H
Guo
Rainer D
RD
Beck