High-Entropy Oxide Toward Practical Hydrogen Production From Alkaline Fresh and Seawater

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• High-entropy oxides (HEOs) are promising electrocatalysts due to tunable properties and stability.
• Electrocatalyst stability in concentrated alkaline solutions and seawater remains a challenge for hydrogen evolution reaction (HER).

Purpose of the Study:

• To synthesize non-equimolar (VCrMnFeCo)O HEO microstructures using mechanical alloying.
• To evaluate the HER activity and durability of the synthesized HEOs in alkaline and seawater electrolytes.
• To investigate the structural evolution of the catalyst under operational conditions.

Main Methods:

• Mechanical alloying for HEO synthesis.
• Electrochemical evaluation of hydrogen evolution reaction (HER) activity and durability.
• Accelerated durability testing (ADT) over 5000 CV cycles.
• Post-mortem structural and elemental analysis of recovered catalysts.

Main Results:

• The (VCrMnFeCo)O HEO catalyst demonstrated excellent HER activity and durability in 6 m KOH and 1 m KOH (seawater).
• The catalyst exhibited low overpotentials and high stability during ADT.
• In situ reduction and element redistribution enhanced catalytic activity during continuous operation.

Conclusions:

• Mechanically alloyed HEOs are effective and stable electrocatalysts for HER in diverse electrolytes.
• The study bridges materials design with practical applications in sustainable hydrogen generation.
• Developed HEOs show potential for both freshwater and seawater electrolysis.