Adsorption and Dissociation of Carbon Trioxide on Ag(100)

Using density functional theory methods, we have studied carbon trioxide, its adsorption and dissociation on Ag(100). In the gas phase, two isomers are found, D-3/t and C-2v, With the latter of 2.0 kcal mol(-1) lower in energy at the PW91PW91/6-31G(d) level. For CO3 on Ag(100), the calculated adsorption energy is 91.2 and 89.1 kcal mol(-1) for the bi-coord perpendicular and tri-coord parallel structures, respectively. Upon the adsorption, 0.50 similar to 0.56 electron is transferred from silver to CO3, indicative of significant ionic characters of the adsorbate-surface bonding. In addition, the geometry of CO3 is largely changed by its strong interaction with silver. For CO3(ad) -> O-(ad) + CO2(gas), the energy barrier is calculated to be 19.8 kcal mol(-1) through the bi-coord path. The process is endothermic with an enthalpy change of +17.3 similar to +26.7 kcal mol(-1) and the weakly chemisorbed CO2 is identified as an intermediate on the potential energy Surface. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 946-952, 2010