Probing Single Pt Atoms in Complex Intermetallic Al₁₃Fe₄

Area of Science:

• Materials Science
• Solid-State Chemistry
• Catalysis

Background:

• Complex metallic alloys (CMAs) like Al13Fe4 exhibit unique electronic and structural properties.
• Single-atom catalysis is a frontier in materials science, offering high efficiency and selectivity.
• Understanding the local atomic environment is crucial for designing effective single-atom catalysts.

Purpose of the Study:

• To investigate the atomic structure and site preference of platinum (Pt) single atoms doped into monoclinic Al13Fe4.
• To evaluate the catalytic performance of Pt single atoms in Al13Fe4 for propyne hydrogenation.
• To elucidate the relationship between the local atomic structure and catalytic activity of single-atom Pt.

Main Methods:

• Single crystal growth of Al13Fe4 using the Czochralski method.
• High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) for atomic-resolution imaging.
• Single-crystal X-ray diffraction (SC-XRD) for precise structural determination.

Main Results:

• Platinum atoms were successfully dispersed as single atoms within the Al13Fe4 matrix, substituting iron sites.
• A strong preferential substitution of Pt at the Fe(1) site was observed.
• Surface single-atom Pt sites exhibited lower activity and selectivity in propyne hydrogenation compared to Al2Pt and bulk Pt.

Conclusions:

• The atomic structure of Pt-doped Al13Fe4 was precisely determined, revealing single-atom dispersion and Fe(1) site preference.
• The catalytic performance of single-atom Pt is significantly influenced by its local coordination environment, particularly bonding with surrounding aluminum atoms.
• These findings provide critical insights into the structure-activity relationships of single-atom catalysts in complex metallic alloys.