Investigation of the doped transition metal promotion effect on CO2 chemisorption on Ni (1 1 1)

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The chemisorption of CO2 on the pure Ni (111) and doped Ni (111) by transition metal (Co, Rh, Cr, Ce, La) were investigated by using the generalized gradient approximation (GGA) and the Perdew–Burke–Emzerhof (PBE) functional. The optimized structure of doped metal surface showed that Rh, Cr, Ce, La atoms upward shift from the surface of Ni (111) plane, while the atom radius of Co is the minimum offset which lead to the height is −0.03Å. The ability of CO2 chemisorption follows the order of La/Ni (111)>Ce/Ni (111)>Cr/Ni (111)>Co/Ni (111)>pure Ni (111). It is exothermic when CO2 chemisorbed on Cr/Ni (111) Ce/Ni (111) and La/Ni (111), while it is endothermic on the Co/Ni (111) and pure Ni (111). CO2 molecular chemisorbed on all the metal surfaces are negatively charged, result from the electron transfer between the metal surfaces and the CO2 molecular. The transition metals La, Ce and Cr can promote the transformation of electron and make the CO bonds longer than the pure Ni (111). We also analyzed the dissociation of CO2 on the Ni-based surface and found that the La/Ni (111) surface is the preference surface for the dissociation of CO2, which improved the ability to hinder carbon deposition.