Electron probe and auger electron microprobe characterization of modified Cu-based amorphous alloys

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Amorphous alloys of copper with zirconium, hafnium, and titanium are potential catalyst precursors.
• Surface modification is crucial for activating these alloys into efficient catalytic materials.

Purpose of the Study:

• To investigate surface morphology and chemical composition changes in Cu-Zr, Cu-Hf, and Cu-Ti amorphous alloys after modification.
• To understand how aging and hydrogen charging affect alloy surfaces for catalytic applications.

Main Methods:

• Surface modification via aging in air (dry corrosion) and hydrogen charging.
• Analysis of surface morphology and chemical composition using techniques like Auger spectroscopy.
• Cross-sectional examination of modified alloy ribbons.

Main Results:

• Aging in air forms a copper bilayer on ZrO x or HfO x supports, creating a large specific surface area of copper.
• Hydrogenation followed by air exposure disintegrates ribbons into smaller pieces covered with copper clusters on an oxide underlayer.
• Cu-Ti alloy showed stability in air, resisting expected modification, while other alloys formed distinct catalytic surfaces.

Conclusions:

• Surface modification, particularly through controlled aging or hydrogenation, effectively transforms amorphous Cu-based alloys into stable and efficient catalysts.
• The formation of a high-surface-area copper phase on oxide supports is key to the enhanced catalytic performance.
• Different alloy compositions (Cu-Ti vs. Cu-Zr/Cu-Hf) exhibit distinct responses to modification, influencing their suitability for specific catalytic applications.