Sub-2 nm Microstrained High-Entropy-Alloy Nanoparticles Boost Hydrogen Electrocatalysis.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• High-entropy alloys (HEAs) exhibit unique properties due to lattice distortion.
• Lattice distortion in HEAs influences surface adsorption and electrocatalytic activity.
• The role of microstrain in HEA electrocatalysis remains underexplored.

Purpose of the Study:

• To investigate sub-2nm IrRuRhMoW HEA nanoparticles for alkaline hydrogen oxidation (HOR) and evolution reactions (HER).
• To understand the impact of lattice distortion-induced microstrain on HEA catalytic performance.
• To correlate catalyst structure and electronic properties with enhanced electrocatalytic activity.

Main Methods:

• Synthesis of sub-2nm IrRuRhMoW HEA nanoparticles.
• Electrocatalytic performance testing for HOR and HER in alkaline media.
• Experimental characterizations (e.g., XRD, TEM, XPS) and theoretical calculations (e.g., DFT) to analyze electronic structure and adsorption properties.

Main Results:

• IrRuRhMoW HEA nanoparticles exhibit significant lattice distortion and microstrain.
• Optimized electronic structure (downshifted d-band center) and enhanced oxophilicity were observed.
• Achieved remarkable HOR kinetic current density (8.09 mA µg^-1_PGM) and HER turnover frequency (5.93 H₂ s^-1).
• Performance significantly surpasses non-HEA and commercial Pt/C catalysts.

Conclusions:

• Lattice distortion-induced microstrain in HEAs is a key factor for enhancing HOR and HER.
• The synergistic effects of ligand and microstrain effects optimize hydrogen and hydroxyl adsorption.
• IrRuRhMoW HEA nanoparticles represent a promising non-noble metal catalyst for efficient alkaline electrocatalysis.