A periodic DFT study of water and ammonia adsorption on anatase TiO2 (001) slab

Water and ammonia adsorption mechanisms on anatase TiO2 (001) slab surface are investigated by means of periodic DFT approach. Molecular and dissociative adsorption energies for water are calculated to be − 15 kcal/mol and − 32 kcal/mol, respectively. Similarly, molecular and dissociative adsorption energies of ammonia on the same surface are found as − 25 kcal/mol and − 20 kcal/mol. A reverse result in this order is reached for the previous case of ONIOM cluster study (− 23 kcal/mol and − 37 kcal/mol, respectively). The vibration frequency values are computed for the optimized geometries of adsorbed water and ammonia molecules on anatase TiO2 (001) slab surface and compared with the values reported in the literature.