科研之友
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摘要
We studied the adsorption of CO molecules on perfect and Pt-adsorbed t-ZrO2(101) surfaces using a periodic slab model by PW91 of generalized gradient approximation (GGA) within the framework of density functional theory. The results indicated that the second sub-surface oxygen and the second bridge sites are the most stable adsorbed sites for CO and Pt on the ZrO2(101) surface, respectively. When the coverage is 0.25 ML (monolayer) the most stable models were obtained with adsorption energies of 56.2 and 352.7 kJ.mol(-1). The most stable model of CO adsorbed on the Pt/t-ZrO2(101) surface was obtained by C-end adsorption with an adsorption energy of 323.8 kJ . mol(-1). We considered vibrational frequency calculations, density of states and the Mulliken population of the adsorption systems before and after adsorption and these were compared for CO and Pt adsorption onto the ZrO2 surface. The results indicate that the C - O bond length of 0.1161 nm after adsorption at the C-end is elongated compared with the 0.1141 and 0.1136 nm of free and adsorbed on ZrO2. The vibrational frequency of CO at 2018 cm(-1) is red-shifted compared with free CO. CO has some positive charge after adsorption and charge transfer is predominantly by the pi back-donation bonding mechanism of the Pt 5d -> CO 2 pi orbital.
