Regulating Surface Faceting as a Kinetic Switch for Core-Shell Nanoparticle Crystallization Pathways

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Crystallization

Background:

• Nanoparticle morphology critically influences physical and chemical properties.
• Mechanisms governing nanoparticle shape during crystallization are not fully understood.

Purpose of the Study:

• To elucidate the fundamental mechanisms controlling the morphology of binary core-shell nanoparticles.
• To identify the kinetic factors governing nanoparticle shape determination.

Main Methods:

• Investigated binary platinum-gold (Pt@Au) core-shell nanoparticles as a model system.
• Analyzed the effect of shell-to-core atomic ratio on nucleation modes.
• Examined the role of surface faceting and nucleation site on final nanoparticle morphology.

Main Results:

• Identified a kinetic bifurcation between surface-nucleation and inner-nucleation modes.
• Discovered a 'kinetic switch' regulated by the shell-to-core atomic ratio.
• Demonstrated that low shell concentrations favor surface nucleation and twinned structures, while increased shell concentrations lead to inner nucleation and single-crystalline structures.

Conclusions:

• Nanoparticle morphology is governed by a kinetic switch in nucleation modes, not solely thermodynamic stability.
• Shell-induced disruption of surface faceting dictates the shift in nucleation site.
• Established a mechanistic link between nucleation position and final morphology, enabling predictive design of binary nanomaterials.