High-entropy RuO₂ catalyst with dual-site oxide path for durable acidic oxygen evolution reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Durable acidic oxygen evolution reaction (OER) catalysts are essential for industrial proton exchange membrane water electrolyzers.
• Current OER catalysts often face stability challenges under demanding operating conditions.

Purpose of the Study:

• To develop highly stable and efficient OER catalysts for proton exchange membrane water electrolyzers.
• To elucidate the catalytic mechanism of novel high-entropy atom-modified RuO2 catalysts.

Main Methods:

• Incorporation of high-entropy atoms (Co, Ni, Cu, Mn, Sm) into RuO2 (RuO2-HEAE) via annealing.
• In situ differential electrochemical mass spectrometry (DEMS) and operando Attenuated Total Reflection Surface-Enhanced Infrared Absorption Spectroscopy (ATR-SEIRAS).
• Quantitative Fourier-transformed extended X-ray absorption fine structure (FT-EXAFS) fitting and density functional theory (DFT) calculations.

Main Results:

• RuO2-HEAE exhibits remarkable stability (>1500 h at 100 mA cm⁻²).
• A mechanistic shift from adsorbate evolution mechanism (AEM) to a dual-site oxide path mechanism (OPM) was observed.
• Elongated Ru-M distance in the second coordination shell of RuO2-HEAE facilitates direct O-O coupling.

Conclusions:

• The OPM-type RuO2-HEAE catalyst demonstrates superior durability (~1500 h at 1 A cm⁻²), outperforming most reported RuO2-based catalysts.
• This study provides fundamental insights into designing highly stable catalysts for proton exchange membrane water electrolysis.
• The findings pave the way for advanced catalyst design for efficient hydrogen production.