Formic acid adsorption and decomposition on clean and atomic oxygen pre-covered Cu(100) surfaces

Area of Science:

• Surface Science
• Heterogeneous Catalysis
• Materials Chemistry

Background:

• Understanding formic acid interactions with metal surfaces is crucial for catalysis.
• The role of surface modifiers, like atomic oxygen, in chemical reactions requires detailed investigation.
• Copper surfaces are widely studied for their catalytic properties.

Purpose of the Study:

• To investigate formic acid adsorption and decomposition on clean and oxygen-modified Cu(100) surfaces.
• To elucidate the effect of atomic oxygen on reaction pathways and product formation.
• To determine the role of surface oxygen in formic acid chemistry.

Main Methods:

• Utilized surface science techniques: scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and infrared reflection-absorption spectroscopy (IRRAS).
• Studied formic acid adsorption on clean Cu(100), O-(2×2)R45° Cu(100), and oxygen-modified Cu(100) with local O-c(2×2) structure.
• Employed temperature-programmed desorption (TPD) to analyze decomposition products.

Main Results:

• The O-(2×2)R45° Cu(100) surface showed inertness to formic acid adsorption at 300 K.
• Bidentate formate formed on clean and oxygen-modified surfaces, with distinct adsorption geometries.
• Formate decomposed into H2 and CO2 on clean Cu(100) above 390 K, but formed H2O and CO2 (starting at 370 K) on oxygen-modified surfaces, indicating oxygen's catalytic role.

Conclusions:

• Surface atomic oxygen plays a critical role in dictating formic acid adsorption behavior.
• Oxygen modifies the decomposition pathway of adsorbed formate species.
• The presence of surface oxygen promotes formate decomposition and influences the formation of H2O and CO2.