Heteroatom dopants overcome the activity-stability trade-off in RuO₂ for acidic oxygen evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Ruthenium dioxide (RuO2) is a promising electrocatalyst for the oxygen evolution reaction (OER) in acidic media, but achieving both high activity and stability remains a challenge.
• Conventional strategies often lead to a trade-off between catalytic activity and long-term durability.
• Iridium dioxide (IrO2) is the benchmark but is scarce and expensive, driving the search for alternatives.

Purpose of the Study:

• To develop a highly active and stable RuO2-based electrocatalyst for the oxygen evolution reaction.
• To overcome the inherent activity-stability trade-off in RuO2 catalysts.
• To investigate the synergistic effects of tantalum (Ta) and boron (B) co-doping on RuO2 nanostructures.

Main Methods:

• Synthesis of nanoporous RuO2 co-doped with Ta and B (Ta/B-RuO2).
• Characterization of the material's structure, including Ru-O-Ta frameworks and Ru-O-B active sites.
• Electrochemical evaluation of the catalyst's performance for the oxygen evolution reaction, including overpotential, Tafel slope, and durability tests.
• Testing in proton-exchange membrane water electrolyzers.

Main Results:

• Successfully constructed Ta and B co-doped nanoporous RuO2 with unique Ru-O-Ta frameworks and Ru-O-B active sites.
• The Ru-O-Ta frameworks enhanced stability by mediating bridging oxygen and replenishing oxygen vacancies.
• The Ta/B-RuO2 catalyst exhibited a low overpotential (170 mV at 10 mA cm-2), a favorable Tafel slope (44 mV dec-1), and excellent durability.
• Proton-exchange membrane water electrolyzers with Ta/B-RuO2 achieved 1.0 A cm-2 at 1.6 V and maintained stable operation for 120 hours at 200 mA cm-2.

Conclusions:

• Ta and B co-doping effectively addresses the activity-stability trade-off in RuO2 for the oxygen evolution reaction.
• The developed Ta/B-RuO2 catalyst demonstrates superior performance and durability, making it a viable alternative to IrO2.
• This work provides a new strategy for designing advanced electrocatalysts for efficient water splitting.