Decomposition of methanol activated by surface under-coordinated Pd on layered PdTe₂

Area of Science:

• Materials Science
• Surface Science
• Catalysis

Background:

• Layered transition metal dichalcogenides like PdTe₂ are explored for catalytic applications.
• Methanol decomposition is a key reaction in chemical synthesis and energy conversion.
• Surface defects significantly influence catalytic activity and reaction pathways.

Purpose of the Study:

• To investigate the methanol decomposition reactivity of PdTe₂.
• To understand the role of surface under-coordinated palladium (Pd_uc) sites.
• To elucidate the reaction mechanisms and identify key intermediates and products.

Main Methods:

• Controlled Ar ion bombardment to create surface Te vacancies and Pd_uc sites.
• Adsorption and decomposition studies of methanol (CH₃OH) on PdTe₂ surfaces.
• Analysis of reaction intermediates and gaseous products using surface science techniques.

Main Results:

• Methanol decomposition on Pd_uc sites involves competing dehydrogenation and C-O bond cleavage.
• Significant conversion of methanol to CHₓ* (x=2,3) and CHₓO* intermediates observed at 180 K.
• High reaction probability (>40%) yielding H₂, formaldehyde, methane, and water.
• Preferential hydrogenation of CHₓ* intermediates suppressed carbon (C*) formation.
• Comparison with PtTe₂ highlights the importance of electronic structure in reactivity and selectivity.

Conclusions:

• PdTe₂ surfaces with Pd_uc sites are efficient catalysts for methanol decomposition.
• The catalytic performance is attributed to geometric and electronic effects of Pd_uc sites.
• The catalyst demonstrates resistance to carbon poisoning due to suppressed C* formation.