DFT studies of the adsorption and dissociation of H_2O on the Al13 cluster: Origins of this reactivity and the mechanism for H _2 release

摘要

A theoretical study of the chemisorption and dissociation pathways of water on the Al13 cluster was performed using the hybrid density functional B3LYP method with the 6-311+G(d, p) basis set. The activation energies, reaction enthalpies, and Gibbs free energy of activation for the reaction were determined. Calculations revealed that the H_2O molecule is easily adsorbed onto the Al_(13) surface, forming adlayers. The dissociation of the first H_2O molecule from the bimolecular H _2O structure via the Grotthuss mechanism is the most kinetically favorable among the five potential pathways for O-H bond breaking. The elimination of H_2 in the reaction of an H_2O molecule with a hydrogen atom on the Al cluster via the Eley-Rideal mechanism has a lower activation barrier than the elimination of H_2 in the reaction of two adsorbed H atoms or the reaction of OH and H. Following the adsorption and dissociation of H_2O, the structure of Al_(13) is distorted to varying degrees.