CO adsorption on molybdenum carbides and molecular simulation

Monte Carlo simulation was carried out for the adsorption of CO an beta -Mo 2C with various C/Mo atomic ratios. The CO adsorption on beta -Mo2C showed the minimum value of the self-diffusion coefficient and the maximum value o f the adsorption energy at C/Mo = 0.40, in accord with the experimental dat a of total CO uptake an the beta -Mo2C0.82 (C/Mo = 0.41). The molecular dyn amics of the CO adsorption predicts the approach of CO to the surface of be ta -Mo2C. The CO molecule preferably adsorbs on carbon deficient sites in t he top layer (the molybdenum atom is in the second layer) and molybdenum at oms neighboring the carbon deficient sites of beta -Mo2C. The simulated mol ecular dynamics suggested that the CO molecule hopped from the molybdenum a tom to the carbon deficient site in the top layer, being displaced 90 degre es by each turn.