CH4 dissociation on the perfect and defective MgO(0 0 1) supported Ni4

Abstract A theoretical understanding of CH 4 dissociation on Ni-based catalysts is of great importance for the development of CH 4 reforming catalysts with high activity and carbon-deposition resistance. Based on comparisons of CH 4 dissociation on perfect and defective MgO supported Ni 4 , as well as Ni(1 1 1), the effects of the strong interactions between Ni 4 and MgO on CH 4 dissociation are systematically investigated by density functional theory (DFT) calculations. Our results indicate that the interaction between Ni 4 and the defective MgO is stronger than for the perfect MgO. Consequently, the adsorptions of CH x ( x  = 0–4) are weaker than those on the perfect Ni 4 /MgO. Hirshfeld charge analysis shows that electrons are transferred from MgO to Ni 4 , then to CH x adspecies; the stronger interactions between Ni 4 and MgO lead to less electronic transfer from Ni 4 to adspecies, which result in weaker adsorption of CH x . Potential energy surface calculations of CH 4 dissociation indicate that there are lower energy barriers for the sequent dissociations of CH 4  → CH 2  + 2H and an appropriate barrier of CH oxidation matching up with that of CH 2 further dissociation on the model catalyst of Ni 4 supported on defective MgO. This might be an elementary requirement for an excellent CH 4 reforming catalyst, and may shed light on experimental catalyst development.