Misoriented high-entropy iridium ruthenium oxide for acidic water splitting

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient catalysts are crucial for acidic oxygen evolution reaction (OER) in proton exchange membrane water electrolyzers (PEMWEs) for hydrogen production.
• Developing catalysts with enhanced activity and stability is a key challenge.

Purpose of the Study:

• To develop a novel quinary high-entropy ruthenium iridium-based oxide (M-RuIrFeCoNiO2) catalyst using a fast, nonequilibrium strategy.
• To investigate the catalyst's performance for the acidic oxygen evolution reaction (OER).

Main Methods:

• Fast, nonequilibrium synthesis of quinary high-entropy oxide (M-RuIrFeCoNiO2).
• Electrochemical characterization of OER performance in 0.5 M H2SO4.
• Microstructural analyses, density functional calculations, and isotope-labeled differential electrochemical mass spectroscopy (DDEMS).

Main Results:

• The M-RuIrFeCoNiO2 catalyst achieved a low overpotential of 189 mV at 10 mA/cm² for OER.
• Abundant grain boundaries (GB) and integrated foreign metal elements enhanced the activity and stability of RuO2.
• A PEMWE with the catalyst operated stably at 1 A/cm² for over 500 hours.

Conclusions:

• The study demonstrates a pathway to design high-performance OER electrocatalysts by integrating diverse components and grain boundaries.
• This approach overcomes the thermodynamic solubility limits for metal elements in catalyst design.