Dual-Descriptor-Guided Screening of Stable Metal-Doped RuO₂ Catalysts for Acidic Oxygen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Doping ruthenium dioxide (RuO2) with metallic elements is crucial for enhancing proton-exchange membrane water electrolyzer (PEMWE) efficiency.
• Identifying optimal dopants is complex due to intertwined structural, electronic, and thermodynamic factors.

Purpose of the Study:

• To develop a robust framework for screening stable RuO2-based electrocatalysts for PEMWEs.
• To utilize computed Pourbaix diagrams and Ru-O bond length analysis as dual descriptors for dopant evaluation.

Main Methods:

• Computed E-pH Pourbaix diagrams were used to assess dopant-induced thermodynamic stability of RuO2.
• Formation energies of different oxygen-coordination states (O-covered, pristine, O-depleted) were compared.
• Ru-O bond length analysis was employed to understand structural influences on dopant stability.

Main Results:

• Pourbaix diagrams revealed metal-dependent thermodynamic stability regions (SRs) and identified critical pH and potential thresholds.
• Ru-O bond length analysis showed that longer bonds suppress RuO4 formation and shorter bonds reduce Ru3+ formation.
• A volcano-type relationship between SR and Ru-O bond length was established, leading to the identification of eight promising dopants (Rh, Zn, Ga, Bi, Mn, Nb, Sn, Os).

Conclusions:

• The combined thermodynamic and structural descriptors provide an effective and universal method for screening stable Ru-based electrocatalysts.
• This approach offers significant potential for accelerating the discovery of advanced materials for water electrolysis.