How Rh surface breaks CO₂ molecules under ambient pressure.

Area of Science:

• Catalysis
• Surface Science
• Chemical Engineering

Background:

• Carbon dioxide (CO2) utilization is key for sustainable fuel synthesis (methane, methanol).
• Understanding reaction intermediates like carbonyl and formate groups is vital for optimizing catalytic yields.
• The initial surface reaction mechanisms of CO2 remain poorly understood at the molecular level.

Purpose of the Study:

• To investigate the spontaneous dissociation of carbon dioxide (CO2) on a model rhodium (Rh) catalyst.
• To elucidate the molecular-level mechanisms and intermediate structures involved in CO2 activation on metal surfaces.

Main Methods:

• Direct observation of CO2 dissociation using scanning tunneling microscopy (STM).
• Surface analysis via near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS).
• Theoretical insights from computational calculations.

Main Results:

• Observed spontaneous CO2 dissociation on a Rh(111) surface at room temperature and 0.1 mbar CO2.
• Demonstrated the transformation of linear CO2 to a bent, chemically active structure at the interface.
• Identified non-uniform charge transfer between adsorbed CO2 and Rh atoms.
• Provided evidence for O-CO bond cleavage and the formation of ordered (2×2)-CO intermediates.

Conclusions:

• The study provides direct molecular-level insights into CO2 dissociation on rhodium.
• Understanding these initial steps is critical for designing efficient catalysts for CO2 conversion.
• The findings contribute to the fundamental knowledge of surface chemistry relevant to sustainable energy.