Interstitial-Hydrogen-Modulated Subnanometer PdPtIrCoNiH High-Entropy Hydride Nanowires for Efficient Hydrogen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The slow Volmer step (water dissociation/formation) is a key kinetic limitation in alkaline hydrogen electrocatalysis.
• Developing efficient electrocatalysts is crucial for advancing hydrogen fuel cells and water electrolyzers.

Purpose of the Study:

• To engineer a high-entropy hydride catalyst overcoming the Volmer step limitation.
• To investigate the catalytic activity and performance of the novel catalyst in hydrogen oxidation and evolution reactions.

Main Methods:

• Synthesis of PdPtIrCoNiH15 high-entropy hydride nanowires.
• Electrochemical characterization of hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) activity.
• Operando X-ray spectroscopies and Density Functional Theory (DFT) calculations to elucidate the catalytic mechanism.

Main Results:

• PdPtIrCoNiH15 nanowires exhibited high mass activities for HOR (8.02 A mgPGM-1) and HER (4.55 A mgPGM-1).
• Interstitial hydrogen induced lattice expansion, buffered structural distortion, and optimized binding energies for key intermediates.
• Demonstrated excellent performance in anion-exchange membrane fuel cells (1.37 W cm-2) and water electrolyzers (1.626 V at 1 A cm-2 with 71 μV h-1 degradation).

Conclusions:

• High-entropy design combined with interstitial hydrogen engineering effectively overcomes kinetic limitations in alkaline hydrogen electrocatalysis.
• The PdPtIrCoNiH15 catalyst offers a promising pathway for efficient and durable hydrogen-based energy conversion devices.