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Why in News?
- Scientists from Ulm University (Germany) and the University of Nottingham (UK) have discovered a new “hybrid” state of matter in metallic nanoparticles that simultaneously exhibits solid and liquid properties.
The Hybrid State
- Definition: A unique atomic structure where a single metallic nanoparticle (like platinum, gold, or palladium) contains both stationary (solid-like) and rapidly moving (liquid-like) atoms at the same time.
- Mechanism (Atomic Corralling):
- Nanoparticles are deposited on graphene, which contains tiny gaps or “point defects.”
Individual metal atoms get trapped in these gaps and remain stationary, even when the rest of the particle melts. When these stationary atoms align at the edge, they form a “ring” or corral that traps the moving liquid core inside.
- Discovery Technique: Observed using High-Resolution Transmission Electron (HRTE) microscopy, where stationary atoms appear as distinct dots while the liquid core appears blurry due to high-speed motion.
- Unique Property (Supercooling): These “corralled” nanoparticles can remain liquid at temperatures 200-300°C lower than their normal freezing point (e.g., platinum staying liquid at 350°C instead of freezing at 500°C).
- Structural Outcome: Upon eventual solidification, the material does not form a standard crystal lattice; instead, it becomes a disordered (amorphous) solid.
- Industrial Significance (Catalysis):
- Hydrogen Fuel Cells: Platinum on carbon is a key catalyst for proton exchange membrane fuel cells.
- Prevention of Clumping: This hybrid state could “pin” particles to the surface, preventing them from clumping together (sintering) or losing effectiveness (“poisoning”), thereby extending the life of fuel cells in electric vehicles.
