Redispersion strategy for high-loading carbon-supported metal catalysts with controlled nuclearity

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Low-nuclearity metal catalysts, including single atoms and small clusters, are highly promising for various applications.
• Current synthesis methods offer precise nuclearity control but lack industrial scalability and effectiveness for high metal loadings.

Purpose of the Study:

• To develop a scalable gas-phase redispersion strategy for preparing supported low-nuclearity metal catalysts.
• To achieve high metal content (up to 10 wt%) and precise control over metal site nuclearity.

Main Methods:

• Sequential gas-phase treatment with acetylene (C2H2) and hydrogen chloride (HCl) to redisperse ruthenium (Ru), rhodium (Rh), and iridium (Ir) nanoparticles.
• Characterization using X-ray absorption spectroscopy, electron paramagnetic resonance, and time-resolved mass spectrometry.

Main Results:

• Successfully dispersed ≈1 nm nanoparticles of Ru, Rh, and Ir into small clusters and single atoms on activated carbon.
• Identified avoidance of nanoparticle overchlorination as critical for effective redispersion.
• Demonstrated precise size control (±0.1 nm) by regulating the number of C2H2-HCl treatment cycles.
• Elucidated a layer-by-layer redispersion mechanism involving metal species migration and rechlorination.

Conclusions:

• The presented gas-phase redispersion strategy is effective for producing high-density, tuneable metal sites on carbon supports.
• This method offers a scalable route for industrial catalyst preparation with controlled low-nuclearity metal species.