|標題:||Adsorption Configurations and Reactions of Nitric Acid on TiO2 Rutile (110) and Anatase (101) surfaces|
|作者:||Chang, Ching Yi|
Lin, M. C.
Institute of Molecular science
|摘要:||The adsorption and reactions of the monomer and dimer of nitric acid on TiO2 rutile (110) and anatase (101) surfaces have been studied by first-principles density functional theory with ultrasoft pseudopotential approximation. The most stable configuration of HNO3 on the rutile surface is a molecular monodentate adsorbed on the 5-fold coordinated Ti atom with the hydrogen bonded to a neighboring surface bridging oxygen with the adsorption energy of 6.7 kcal/mol. It can dissociate its H atom to a nearest bridged oxygen with almost no barrier to produce NO3(a) + H(a). The rotation of NO3 requires a barrier of 12.2 kcal/mol to form the didentate configuration, Ti-5c-ON(O)-Ti5cH-O-2,(a), which adsorbs on two 5-fold coordinated Ti atoms with the adsorption energy of 16.5 kcal/mol. In the case of the adsorption of 2HNO(3) molecules, the most stable configuration, 2(Ti-5c-ON(O)OH...O-2c(a)), has a structure similar to two single HNO3 adsorbates on two 5-fold coordinated Ti atoms with the adsorption energy of 12.8 kcal/mol, which is about twice that of the single HNO3 molecule. The result suggests that the interaction of the two planar HNO3 adsorbates is negligible. The dehydration from 2(Ti-5c-ON(O)OH...O(2)c(a)) forming N2O5(a) + H2O(a) requires an energy barrier of 46.2 kcal/mol, indicating that the dimerization of the two HNO3(a) is difficult. Similar adsorption phenomena appear on the anatase (101) surface. In addition, we find that the coadsorption of hydrogen plays a significant role in the adsorption energies of adsorbates, especially for the NO3 radical, which may be employed as a linker between semiconductor quantum dots such as InN and the TiO2 surface.|
|期刊:||JOURNAL OF PHYSICAL CHEMISTRY C|
|Appears in Collections:||Articles|