Stability of Ni Clusters and the Adsorption of CH4: First-Principles Calculations

Structural, magnetic and adsorption properties of Nin (n = 2-16, 21, 55) clusters have been investigated based on density funciontal theory (DFT) with the spin polarized generalized gradient approximation, using the Perdew-Burke-Ernzerhof functional. The most stable isomers have been selected to study the adsorption of methane CH4 and methyl CH3. It is found that the CH4 molecule adsorbs on the top site for all clusters considered. The most selective Nin clusters are the tetrahedron (n = 4) and icosahedral clusters due to high-coordinated edge atoms (n = 13, 21, and 55). For CH3, stronger adsorption tendencies were found with similar patterns. Our results show that clusters with n = 6, 10, and 13 with complete atomic shells are relatively more stable. Besides, they perform the lowest adsorption for CH3, indicating that they possess such a desirable property of a higher carbon poisoning resistance, than for the rest of the clusters. This result can be understood in terms of the electronic stability and localization of the frontier molecular orbitals. (Chemical Equation Presented). © 2015 American Chemical Society.

Calculations; Carbon; Density functional theory; Isomers; Methane; Molecular orbitals; Nickel; Adsorption properties; Chemical equations; Electronic stability; First-principles calculation; Frontier molecular orbitals; Generalized gradient approximations; Icosahedral clusters; Perdew-burke-ernzerhof; Adsorption

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