Ruthenium-Manganese Solid Solution Oxide with Enhanced Performance for Acidic and Alkaline Oxygen Evolution Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Hydrogen production via water electrolysis is crucial for clean energy, but faces challenges from sluggish oxygen evolution reaction (OER) kinetics and limited electrocatalyst durability.
• Existing electrocatalysts for proton exchange membrane and alkaline exchange membrane water electrolysers often exhibit poor performance and stability, hindering efficient hydrogen generation.

Purpose of the Study:

• To develop an efficient and durable electrocatalyst for the oxygen evolution reaction (OER) applicable in both acidic and alkaline electrolytes for water electrolysis.
• To investigate the structural and compositional effects of a rutile Ru$_{0.75}$Mn$_{0.25}$O$_{2-δ}$ solid solution oxide on OER performance.

Main Methods:

• Synthesis of a hierarchical porous rutile Ru$_{0.75}$Mn$_{0.25}$O$_{2-δ}$ solid solution oxide.
• Electrochemical characterization of the catalyst's OER activity and durability in acidic (0.5 M H$_{2}$SO$_{4}$) and alkaline electrolytes.
• Comparison of the catalyst's performance against commercial RuO$_{2}$.

Main Results:

• The Ru$_{0.75}$Mn$_{0.25}$O$_{2-δ}$ catalyst exhibited superior OER kinetics in acidic media, with a low Tafel slope of 54.6 mV dec$^{-1}$ and low overpotentials (237 mV at 10 mA cm$^{-2}$, 327 mV at 100 mA cm$^{-2}$).
• Enhanced electrochemically active surface area and increased intrinsic activity due to Mn incorporation (regulating Ru$^{>4+}$ proportion) contributed to the improved performance.
• The catalyst demonstrated excellent OER performance and durability in alkaline electrolyte, attributed to Mn's sacrificial dissolution mitigating Ru leaching.

Conclusions:

• The hierarchical porous rutile Ru$_{0.75}$Mn$_{0.25}$O$_{2-δ}$ solid solution oxide is a highly efficient and durable electrocatalyst for the oxygen evolution reaction.
• This versatile catalyst offers a promising solution for improving hydrogen production efficiency in both acidic and alkaline water electrolysis systems.