Applied Surface Science, Vol.389, 1094-1103, 2016
Structural, electronic and adsorption properties of Rh(111)/Mo(110) bimetallic catalyst: A DFT study
Geometric and electronic characterizations of one monolayer rhodium with Nishiyama-Wassermann (NW) structure on Mo(110) substrate have been performed by density functional theory (DFT) calculations. In the NW structure the Rh atoms form a wavy structure propagating along the [001] direction, characterized by an amplitude of 0.26 angstrom in the [110] direction and by 0.10 angstrom in the [110] direction of the Mo(110) substrate. Strain and ligand effects operating in the rhodium film are distinguished and found to be manifested in the downward shift of the d-band center of the electron density of states (DOS) by 0.11 eV and 0.18 eV, respectively. The shift in the d-band center of Rh DOS predicts a decrease in the surface reactivity toward CO adsorption, which has been verified by detailed calculations of bond energies of CO located at on-top, bridge and hollow adsorption sites. The CO adsorption energies are decreased by about 35% compared to those reported for pure Rh(111), offering novel catalytic pathways for the molecule. An in-depth analysis of the charge transfer and the partial DOS characters upon CO adsorption on the NW-structured Rh(111)/Mo(110) bimetallic catalyst and on the pure Rh(111) surface sheds light on the bonding mechanism of CO and on the governing factors determining its lowered bond energy on the bimetallic surface. (C) 2016 Elsevier B.V. All rights reserved.