(702b) Density Functional Theory Study of Dry Reforming of Methane on Pure Nickel As Well As Transition Metal Overlayer Deposited Nickel Surfaces
In the current work, we present our exhaustive work on the solid state density functional theory (DFT) model results to study theoretically the wide network of elementary reactions comprising the DRM reaction on various facets of pure nickel catalyst, such as Ni(111), Ni(100) and Ni(110) surfaces. Calculations were performed using rev-PBE as exchange-correlation functional within the generalized gradient approximation (GGA) as implemented in the software VASP. Long term interactions such as the van der Waals forces are quite critical for the accurate description of the adsorption energies. Thus the DFT-D3 method of Grimme is used to account for dispersion corrections. Adsorption energies were calculated for all the DRM reaction intermediate species and then subsequently the activation barriers were calculated for all the elementary reactions in the DRM cycle. The catalytic activity of these pure nickel surfaces in terms of DRM reaction rate are then compared to the rates obtained on the single overlayer deposited nickel (X/Ni) surfaces where X is a transition metal such as Cu, Rh and Pd. Electronic structure analysis of various pure as well as overlayer modified surfaces is performed in terms of the d-band theory of catalysis. Our results indicate that the catalyst stability is greatly improved by a transition metal overlayer deposition on nickel surface.
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