Atomic-scale structure and catalytic reactivity of the RuO(2)(110) surface

Area of Science:

• Surface Science
• Catalysis
• Materials Science

Background:

• Oxide surfaces are crucial catalysts, but their reaction mechanisms are not fully understood at the atomic level.
• The role of coordinatively unsaturated sites in oxide catalysis was hypothesized but lacked direct atomic-scale evidence.

Purpose of the Study:

• To elucidate the atomic structure of the Ruthenium Dioxide (RuO2)(110) surface.
• To investigate the mechanism of catalytic carbon monoxide oxidation on RuO2(110).
• To provide atomic-scale verification of a general catalytic mechanism for oxide surfaces.

Main Methods:

• Low-energy electron diffraction (LEED) for surface structure analysis.
• Scanning tunneling microscopy (STM) for atomic-scale imaging.
• Density-functional theory (DFT) calculations for mechanistic insights.

Main Results:

• The RuO2(110) surface features bridging oxygen and coordinatively unsaturated ruthenium atoms.
• Carbon monoxide chemisorbs on these unsaturated sites and reacts with lattice oxygen to form CO2.
• Consumed lattice oxygen is replenished by gas-phase oxygen uptake, maintaining catalytic activity.

Conclusions:

• Atomic-scale evidence supports the role of coordinatively unsaturated sites in RuO2(110) catalysis.
• The study validates the Mars and van Krevelen mechanism for carbon monoxide oxidation on oxide surfaces.
• Findings have broad implications for understanding and designing catalytic reactions on oxide materials.