The mechanism of H2 dissociation and adsorption on Mn-modified Ni(111) surface: A density functional theory-based investigation

The mechanism of H2 dissociative adsorption on Mn-modified Ni(111) surface is investigated and explained using spin-polarized density functional theory (DFT). Potential energy surface (PES) is used to determine the efficient reaction pathway of H2 on the surface. The dissociative adsorption of H2 in the hollow sites with its center-of-mass (CM) positioned on top of Ni atom has low activation barrier. This is lower compared if its CM is on top of the Mn atom. The difference in the reactivity of H2 with Ni and Mn as the CM is corroborated by the positions of the bonding and antibonding orbitals of H2 as it approaches the surface which is verified from local density of states (LDOS). The greater density of states in the region around the Fermi level of the dzz, dxz, and dyz orbitals of the Ni atom explains the low activation barrier obtained for the dissociation of H2 on top of the Ni atom in the Mn-modified Ni(111) surface.