کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5425472 | 1395857 | 2006 | 14 صفحه PDF | دانلود رایگان |

The adsorption of 1,3-cyclohexadiene, 1,4-cyclohexadiene, cyclohexene and cyclohexane on Pt(1Â 1Â 1) was studied using ab initio density functional theory. For 1,3-cyclohexadiene three adsorption modes were distinguished: bridge 1,2-di-Ï/3,4-Ï, hollow 1,4-di-Ï/2,3-Ï and bridge 1,4-di-Ï/2,3-Ï with adsorption energies of â155, â147 and â75Â kJ/mol, respectively. Three stable adsorption modes were also identified for 1,4-cyclohexadiene: bridge quadra-Ï, hollow di-Ï/Ï and bridge di-Ï with adsorption energies of â146Â kJ/mol, â142Â kJ/mol and â88Â kJ/mol, respectively. Cyclohexene was found to adsorb in six modes: 4 di-Ï and 2 Ï-adsorption modes. The preferred configuration was found to be boat di-Ï with an adsorption energy of â81Â kJ/mol. The three other di-Ï adsorption modes have comparable adsorption energies, ranging from â64 to â69Â kJ/mol. Molecular strain and CPt bonding energies are used to elucidate stability trends. Cyclohexane is found to adsorb only at the hollow site whereby the axial hydrogen atoms are positioned over surface Pt-atoms with an adsorption energy of â37Â kJ/mol. The calculations correctly predict the weakening of the axial CH bonds and provide a possible explanation for the large shift in the vibrational frequencies.
Journal: Surface Science - Volume 600, Issue 16, 15 August 2006, Pages 3121-3134