Durable Ru Nanocrystal with HfO₂ Modification for Acidic Overall Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton exchange membrane water electrolysis (PEMWE) requires durable, bifunctional catalysts for efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under acidic conditions.
• Commercialization of PEMWE is hindered by the lack of cost-effective and high-performance catalysts that can withstand harsh acidic environments.

Purpose of the Study:

• To develop a robust bifunctional catalyst for acidic water electrolysis.
• To investigate the synergistic effects of HfO2 modification and confined Ru nanodomains on catalytic activity and stability.

Main Methods:

• Fabrication of a L-Ru/HfO2 heterostructure by confining crystalline Ru nanodomains within a HfO2 matrix.
• Assembly of the catalyst into a proton exchange membrane electrolyzer.
• Electrochemical performance testing, including voltage-current density measurements and stability assessments.
• Analysis of the catalyst's electronic structure and reaction mechanisms using computational methods.

Main Results:

• The L-Ru/HfO2 catalyst demonstrated superior performance, achieving 100 mA cm⁻² at 1.57 V and 300 mA cm⁻² at 1.67 V.
• The catalyst outperformed previously reported Ru-based materials and commercial Pt/C||RuO2 electrolyzers.
• HfO2 modification and small crystalline domain formation effectively suppressed Ru over-oxidation and optimized oxygen binding configurations.
• Enhanced water adsorption/dissociation and moderate hydrogen binding accelerated the HER kinetics.

Conclusions:

• The synergistic effect in L-Ru/HfO2 heterostructures significantly enhances activity and stability for acidic overall water splitting.
• The catalyst maintains Ru metallic state and reduces the energy barrier for the rate-determining OER step.
• This work provides a promising pathway for developing advanced catalysts for efficient and durable water electrolysis.