Identify the Activity Origin of Pt Single-Atom Catalyst via Atom-by-Atom Counting

Area of Science:

• Catalysis
• Materials Science
• Nanotechnology

Background:

• Atom dispersion in supported metal catalysts is critical for catalytic performance.
• Practical catalysts exhibit structural diversity (single atoms, clusters, particles).
• Traditional methods (chemisorption, XAS) provide averaged dispersion data, lacking atomic precision.

Purpose of the Study:

• To develop and apply electron-microscopy-based atom recognition statistics (EMARS) for precise catalyst dispersion quantification.
• To correlate atom dispersion with catalytic activity in a Pt/Al2O3 reforming catalyst.
• To compare EMARS with traditional methods like hydrogen-oxygen titration.

Main Methods:

• Development of electron-microscopy-based atom recognition statistics (EMARS).
• Statistical counting of over 18,000 platinum atoms in a Pt/Al2O3 catalyst.
• In situ microscopy to observe structural and dynamic changes.
• Comparison with hydrogen-oxygen titration for dispersion assessment.

Main Results:

• EMARS redefines catalyst dispersion at atomic precision in real space.
• Catalytic activity for aromatics production directly correlates with Pt single-atom density.
• Pt clusters show no direct activity but can transform into single atoms under specific conditions.
• Hydrogen-oxygen titration introduces significant bias in Pt dispersion assessment.

Conclusions:

• EMARS provides unprecedented atomic-level insight into catalyst structure and dispersion.
• Catalytic roles of different metal species can be identified via atom-resolved statistics.
• EMARS offers a superior method for characterizing practical catalysts compared to traditional techniques.