Switchable Reaction Pathway on RuO₂ via Atomic Co Doping Toward Oxygen Evolution in Acidic Media

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton exchange membrane water electrolysis (PEMWE) faces challenges with Ru-based anode catalyst stability in acidic, oxidizing environments.
• Limited catalyst durability hinders the practical application of PEMWE technology.

Purpose of the Study:

• To synthesize and evaluate Co-doped RuO2 nanocrystals as stable and active oxygen evolution reaction (OER) catalysts for PEMWE.
• To elucidate the mechanism by which cobalt doping enhances catalyst performance and durability.

Main Methods:

• One-step annealing synthesis of Co-exchanged Ru-bpydc derivatives to form Co-doped RuO2 nanocrystals.
• Electrochemical testing for OER performance and long-term stability assessments.
• Advanced characterization (e.g., X-ray photoelectron spectroscopy, electron microscopy) and Density Functional Theory (DFT) calculations.

Main Results:

• Co-doped RuO2 nanocrystals achieved a low OER overpotential (205 mV at 10 mA cm-2) and exceptional stability (>1000 h).
• Cobalt doping increased oxygen vacancies and promoted the adsorbate evolution mechanism (AEM) for OER.
• DFT calculations confirmed optimized oxo-intermediate adsorption energies via Ru-O-Co interactions, enhancing stability.
• The Co-RuOx catalyst demonstrated stable PEMWE anode operation (>100 h at 100 mA cm-2).

Conclusions:

• Co-doping is an effective strategy to enhance the activity and durability of Ru-based OER catalysts for PEMWE.
• The enhanced performance is attributed to modified electronic structures and reaction pathways, particularly promoting AEM.
• This research contributes a viable approach for developing advanced catalysts for efficient water electrolysis.