Trends in the adsorption and decomposition of hydrogen and ethylene on monolayer metal films: A combined DFT and experimental study

Abstract

The combination of density functional theory (DFT) modeling with surface science experiments offers the potential to design catalysts with improved activity and selectivity. In the current paper we report theoretical and experimental studies of the adsorption and decomposition of hydrogen and ethylene on several bimetallic surfaces. DFT calculations predicted that Pd/Mo(1 1 0) and Pt/W(1 1 0) bimetallic surfaces would bind hydrogen and ethylene more weakly than do the corresponding surfaces of the parent metals. The adsorption and decomposition of hydrogen and ethylene on Pd/Mo(1 1 0) and Pt/W(1 1 0) bimetallic systems were investigated using temperature-programmed desorption (TPD), Auger electron spectroscopy (AES), and high-resolution electron energy loss spectroscopy (HREELS) to test the DFT predictions. On the 0.5 and 1.0 ML Pd/Mo(1 1 0) surfaces, the binding strength and the degree of dissociation of hydrogen and ethylene were significantly reduced as compared to Mo(1 1 0) and thick Pd films. Similarly, on 0.5 and 1.0 ML Pt/W(1 1 0) surfaces, TPD results indicated that the degree of dissociation of hydrogen and ethylene was substantially reduced as compared to clean W(1 1 0). HREELS studies of C 2H 4 and C 2D 4 revealed that the adsorption of ethylene on Pt/W(1 1 0) occurred via the weakly π-bonded configuration, which was different from the di-σ bonding on clean W(1 1 0) or Pt(1 1 1).