Water-Based Synthesis of Supported Ultrasmall High-Entropy Alloy Nanoparticles

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• High-entropy alloys (HEAs) show promise for electrocatalysis.
• Existing synthesis methods for HEA nanoparticles are often complex or environmentally unfavorable.
• There is a need for simple, green synthesis routes for HEA nanoparticles.

Purpose of the Study:

• To develop a facile and environmentally benign method for synthesizing ultrasmall HEA nanoparticles.
• To investigate the electrocatalytic performance of these novel HEA nanoparticles.
• To explore the synergistic effects between the HEA nanoparticles and the carbon support.

Main Methods:

• Synthesis of IrPdPtRuRh HEA nanoparticles (1-3 nm) using a hot-injection approach in water.
• Utilized l-ascorbic acid as a reducing agent.
• Direct formation of nanoparticles on a carbon support.

Main Results:

• Successfully synthesized ultrasmall (1.2 ± 0.7 nm) IrPdPtRuRh HEA nanoparticles.
• Achieved uniform dispersion of all five elements within the nanoparticles.
• The supported HEA nanoparticles demonstrated enhanced performance in the alkaline hydrogen evolution reaction compared to a Pt/C benchmark.
• Observed a 30 mV reduction in overpotential to reach 10 mA cm^-2_ECSA.
• Identified a synergistic effect between the carbon support and l-ascorbic acid, increasing metal reduction rates.

Conclusions:

• A simple, water-based hot-injection method enables the synthesis of ultrasmall, multi-element HEA nanoparticles.
• The synthesized HEA nanoparticles exhibit excellent electrocatalytic activity for the hydrogen evolution reaction.
• The carbon support plays a crucial role in enhancing the catalytic performance through synergistic interactions.