Achieving High OER Performance by Tuning the Co/Mn Content in Prussian Blue Analogues.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Growing demand for clean energy drives interest in water-splitting for green hydrogen.
• The oxygen evolution reaction (OER) is a bottleneck in water-splitting due to sluggish kinetics.
• Efficient and cost-effective OER catalysts are crucial for practical applications.

Purpose of the Study:

• To synthesize an inexpensive and tunable FeCoMn Prussian blue analogue (PBA) as an efficient OER catalyst.
• To optimize the Co and Mn ratio for enhanced electrochemical performance.
• To investigate the catalytic mechanism using advanced characterization and computational methods.

Main Methods:

• Straightforward synthesis of FeCoMn Prussian blue analogues (PBAs).
• Electrochemical testing to evaluate OER performance, including overpotential and Tafel slope.
• X-ray absorption spectroscopy (XAS) for electronic structure analysis.
• Density functional theory (DFT) calculations to understand the catalytic mechanism.

Main Results:

• The FeCo$_{0.41}$Mn$_{0.42}$ PBA catalyst exhibited superior OER performance: 260/304 mV overpotential at 10/50 mA cm$^{-2}$.
• Achieved a low Tafel slope of 48 mV dec$^{-1}$ and remarkable stability of 72 hours at 10 mA cm$^{-2}$.
• XAS and DFT revealed optimized electronic density at the Co active site and enhanced conductivity due to Mn and Fe doping.

Conclusions:

• The developed FeCoMn PBA is a cost-effective and highly efficient catalyst for the oxygen evolution reaction.
• Optimized doping with Mn and Fe enhances conductivity and activates key water deprotonation steps.
• This catalyst shows significant potential for advancing green hydrogen production through water-splitting technologies.