Directed Crystallization: Engineering Facet-Specific High-Entropy Alloy Nanocatalysts Toward Advanced Zinc-Air...

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• High-entropy alloys (HEAs) show promise for catalysis, but their complex atomic structures pose synthetic challenges.
• Controlling crystallographic facets and morphology is key to maximizing HEA catalytic efficiency.

Purpose of the Study:

• To develop a novel directed crystallization strategy for synthesizing HEA nanocatalysts with controlled morphology and exposed facets.
• To investigate the catalytic performance of these engineered HEA nanocatalysts in zinc-air batteries.

Main Methods:

• Utilized structure-directing agents (SDAs) and coordination solvents for kinetic control during precursor reduction.
• Synthesized PtRuMoNiCoFe HEA nanocatalysts with tailored dimensionality (0D-2D) and selectively exposed crystal facets, focusing on (111)-facet-rich nanowires.
• Employed theoretical calculations to understand the electronic structure and catalytic mechanisms.

Main Results:

• Achieved synthesis of (111)-facet-rich HEA nanowires with engineered lattices, step edges, and undercoordinated sites.
• Demonstrated that (111) facet exposure optimizes intermediate adsorption/desorption and lowers the redox energy barrier, resulting in an ultra-low redox overpotential gap (ΔE) of 0.68 V.
• The HEA nanowires exhibited a high specific capacity (797.8 mAh g_Zn^-1) and exceptional cycling stability (>650 h) in Zn-air batteries, outperforming commercial catalysts.

Conclusions:

• Established an advanced synthetic paradigm for facet-specific, atomic-level design of HEA catalysts.
• The engineered HEA nanocatalysts demonstrate significant potential for high-performance next-generation energy conversion technologies, particularly in rechargeable batteries.