C–H Bond Activation of Methane via σ–d Interaction on the IrO₂(110) Surface: Density Functional Theory Study

The adsorption and dissociation of methane on the IrO 2 (110) surface were investigated by density functional theory calculations. The adsorption energy of methane obtained in this study is −0.41 eV on the stoichiometric surface and −0.63 eV on the oxygen-rich surface, which are significantly higher than those calculated recently on other different catalytic systems. Analyses from density of states and electron density difference show a special interaction between the C–H bonding orbital and the d z 2 orbital of surface iridium atom. In addition, the first hydrogen atom abstraction of methane by the IrO 2 (110) surface is a reaction with low barrier and high exothermic energy. The lower reaction barrier than the desorption energy indicates that the IrO 2 (110) surface could provide not only high sticking coefficient but also high turnover frequency in methane dissociation reaction.