Growth and Decomposition of Pt Surface Oxides

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Platinum (Pt) thin films are crucial in various catalytic applications.
• Understanding the behavior of Pt surface oxides is essential for optimizing catalytic processes.
• Previous studies have often been limited by characterization conditions.

Purpose of the Study:

• To investigate the formation and thermal stability of Pt surface oxides.
• To elucidate the influence of oxygen pressure and temperature on Pt oxide formation.
• To assess the stability of Pt oxides under different vacuum conditions.

Main Methods:

• In situ ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) was employed.
• Pt thin films were exposed to oxygen at 73 Pa (550 mTorr).
• Surface oxide formation and decomposition were monitored during heating and cooling cycles.

Main Results:

• Pt surface oxides formed gradually upon heating in oxygen, with peak intensity between 217-317 °C.
• Oxide intensity showed complex behavior during cooling, increasing then decreasing.
• Pt oxides partially decomposed under ultra-high vacuum (UHV) pumping and fully decomposed upon heating in UHV.

Conclusions:

• The formation and thermal stability of Pt surface oxides are highly dependent on oxygen partial pressure and temperature.
• Characterizing Pt surfaces with UHV instruments presents challenges due to oxide decomposition.
• These findings are critical for understanding Pt surface states and catalytic mechanisms in diverse environments.