Methane dissociation and methyl diffusion on PdO{100}

The CH4 -> CH3+H dissociation on the defect-free Pd-2O terminated PdO{100} surface is investigated by first principles calculations. CH3 chemisorbs preferentially at O sites, where the adsorption is 0.68 eV more stable than at Pd sites. Analysis of the electronic structure of adsorption geometries reveals that the enhanced stability is due to the strongly covalent character of the bonding between surface O and CH3. However, transition state searches suggest that the Pd atom is the most likely active site for CH4 dissociation. An alternative route toward the most stable chemisorbed state is proposed that involves diffusion of CH3 on the surface.