Dynamic Study of O₂ Adsorption and Dissociation on Pd Low-Index Surfaces

Abstract

The extended LEPS constructed by 5-MP (the 5-parameter Morse potential) is performed. At low coverage, O2 prefers to dissociate on the Pd(100) and (110) surfaces; however, at high coverage, it can stably adsorb in the H−B−H site on the Pd(111) surface and more molecular states are found. The calculation results agree well with the experimental results, especially, the results of O2 on Pd(111) explain well the three precursor states (the superoxo-like state, the peroxo-like and second peroxo-like state) of HREELS and EELS results. Simultaneously, the conceptions of the molecular dissociation limit and the surface dissociation distance are brought forward first, which illuminate the dissociation mechanism of the O2 on the low-index surfaces and offer the answer to the question why is it more difficult for O2 to dissociate on the (111) surface than on the (100) and (110) surfaces?

Theoretical study of NO adsorption/dissociation on Pd (100) and (111) surfaces

“…The Sato parameter ( O -Pd = 0.14 [20] ) and five parameters of O-Pd [25] (listed in Table 1) are cited from our works. From the experimental data, we get the optimization of the other two Sato parameters ( N-O = −0.19 and N-Pd = 0.91) and the five parameters of N-Pd (listed in Table 1).…”

“…It is a pity that the directly dissociated channels are not found, which is different to the O 2 on the Pd (100) [25] surface. The NO molecules are all precursor dissociated when they are close to the Pd (100) surface near T, B, and H sites.…”

“…The vibration frequency of N-O is 610 cm −1 , with the N-O bond stretching to 1.860 ' Å, which is similar to that of O 2 on the Pd (111) surface. [25] For the molecular side interaction, the two atoms do not dissociate and they are present as the molecular adsorption state, though the frequency approaches that of the atoms. This appearance of the state is because the surface dissociation distance √ 6/6 a 0 of the (111) surface is shorter than the molecular dissociation limit (about double the gaseous N-O bond).…”

“…The extended LEPS constructed by 5-MP has been successfully used in the systems of CO-Ni, [21] H 2 -Ni, [24] and O 2 -Pd. [25] Here, we study the adsorption and dissociation of NO on Pd (100) and (111) surfaces with the extended LEPS based on the experimental information from the interaction of NO and Pd. Our efforts will give people a more detailed insight into the NO-Pd (100) and (111) systems, and help people have a more comprehensive understanding of the mechanism of adsorption and dissociation of NO on transition metal low-index surfaces.…”

Adsorption of hydrogen on palladium nanoparticle surfaces

“…Wang et al have applied this potential to investigate many H-Pd systems successfully. [8,22] The potential function for H atom is the model of Baskes [19,35] and it was applied to investigate H embrittlement. [29] Adsorption energy is given by…”