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Adsorption and dissociation of NH 3 on clean and hydroxylated TiO 2 rutile (110) surfaces: A computational study
Author(s) -
Chang JeeGong,
Chen HsinTsung,
Ju ShinPon,
Chang ChingSheng,
Weng MengHsiung
Publication year - 2010
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21690
Subject(s) - adsorption , denticity , rutile , chemistry , dissociation (chemistry) , endothermic process , electronegativity , inorganic chemistry , crystallography , crystal structure , organic chemistry
The adsorption and dissociation of NH 3 on the clean and hydroxylated TiO 2 rutile (110) surfaces have been investigated by the first‐principles calculations. The monodentate adsorbates such as H 3 NTi(a), H 2 NTi(a), NTi(a), H 2 NO(a), HNO(a), NO(a) and HO(a), as well as the bidentate adsorbate, TiNTi(a) can be formed on the clean surface. It is found that the hydroxyl group enhances the adsorption of certain adsorbates on the five‐fold‐coordinated Ti atoms (5c‐Ti), namely H 2 NTi(a), HNTi(a), NTi(a) and TiNTi(a). In addition, the adsorption energy increases as the number of hydroxyl groups increases. On the contrary, the opposite effect is found for those on the two‐fold‐coordinated O atoms (2c‐O). The enhanced adsorption of NH x ( x = 1 − 2) on the 5c‐Ti is due to the large electronegativity of the OH group, increasing the acidity of the Ti center. This also contributes to diminish the adsorption of NH x ( x = 1 − 2) on the two‐fold‐coordinated O atoms (2c‐O) decreasing its basicity. According to potential energy profile, the NH 3 dissociation on the TiO 2 surface is endothermic and the hydroxyl group is found to lower the energetics of H 2 NTi(a)+HO(a) and HNTi(a)+2{HO(a)}, but slightly raise the energetic of TiNTi(a)+3{HO(a)} compare to those on the clean surface. However, the dissociation of NH 3 is found to occur on the hydroxylated surface with an overall endothermic by 31.8 kcal/mol and requires a barrier of 37.5 kcal/mol. A comparison of NH 3 on anatase surface has been discussed. The detailed electronic analysis is also carried out to gain insights into the interaction nature between adsorbate and surface. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011.