Effect of Ni(111) surface alloying by Pt on partial oxidation of methane to syngas: A DFT study

Density functional theory calculations were performed to study the adsorption and dissociation of methane as well as syngas formation over Ni(111) and NiPt(111) aiming to gain insight into the effect of Ni(111) surface alloying on partial oxidation of methane (POM). Results show that Pt-doped Ni(111) surface is beneficial to the adsorption of CHx and H species while unfavorable to the desorption of H2. The process of CH → C + H is found to be the rate-limiting step of successive dehydrogenation of methane on NiPt(111). Especially, the processes of CH4 → CH3 + H and CH3 → CH2 + H proceed more easily on NiPt(111) than on Ni(111). Three potential pathways for CO formation in the POM process were proposed and calculations identified that CH + O → CHO → CO + H are likely to be the main routes for CO formation on Ni(111) with CH + O → CHO as the rate-limiting step. Further calculations reveal that the formation of CO and H2 may be more difficult on NiPt(111) than on Ni(111).