Methane dissociation and methyl diffusion on PdO{100}.

Area of Science:

• Surface Science
• Computational Chemistry
• Catalysis

Background:

• Methane dissociation is crucial for catalytic processes.
• Understanding surface reactions on metal oxides like PdO is key to catalyst design.
• The PdO{100} surface presents a specific catalytic environment for methane activation.

Purpose of the Study:

• To investigate the initial methane (CH4) dissociation pathway on a defect-free Pd-2O terminated PdO{100} surface.
• To determine the preferred adsorption sites and stability of reaction intermediates.
• To identify the active sites for methane dissociation using first-principles calculations.

Main Methods:

• First-principles calculations were employed to model the surface interactions.
• Density Functional Theory (DFT) was used to analyze electronic structures and adsorption energies.
• Transition state searches identified reaction pathways and activation barriers.

Main Results:

• Methyl (CH3) chemisorption is more stable at oxygen sites (0.68 eV) than at palladium sites on the PdO{100} surface.
• The enhanced stability at oxygen sites is attributed to strong covalent bonding between surface oxygen and CH3.
• Palladium atoms were identified as the most probable active sites for the initial CH4 dissociation step.

Conclusions:

• While CH3 intermediates stabilize at oxygen sites, the initial CH4 dissociation is favored at palladium sites.
• Surface diffusion of CH3 may provide an alternative route to the most stable chemisorbed state.
• This study elucidates the complex reaction mechanism of methane dissociation on PdO{100} surfaces.