Manganese-Based Electrocatalysts for Acidic Oxygen Evolution: Development and Performance Evaluation.

Area of Science:

• Electrochemistry and Materials Science
• Catalysis for sustainable energy applications

Background:

• The oxygen evolution reaction (OER) is critical for water electrolysis and sustainable hydrogen production.
• Noble metal catalysts are effective but costly and scarce, necessitating alternative materials.
• Manganese-based compounds are explored as cost-effective, earth-abundant OER catalysts.

Purpose of the Study:

• To synthesize and evaluate manganese antimonates, chlorates, and bromates as noble-metal-free OER catalysts.
• To optimize synthesis conditions using ultrasound-assisted techniques for improved material properties.
• To assess the catalytic performance and stability of synthesized materials in acidic media.

Main Methods:

• Synthesis of Mn antimonates, chlorates, and bromates via ultrasound-assisted techniques.
• Physicochemical characterization using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and surface area analysis.
• Electrochemical evaluation of OER activity and stability, including overpotential and Tafel slope measurements.

Main Results:

• All synthesized manganese compounds showed low surface area and inter-particle porosity with mixed crystalline phases.
• Mn7.5O10Br3, synthesized via ultrasound homogenization and calcination, exhibited the highest OER activity.
• This optimized Mn7.5O10Br3 achieved an overpotential of 153 mV at 10 mA cm-2 and demonstrated short-term stability comparable to IrO2.

Conclusions:

• Ultrasound-assisted synthesis is effective for preparing homogeneous manganese-based OER catalysts.
• Mn7.5O10Br3 is a promising noble-metal-free catalyst for the oxygen evolution reaction.
• Further optimization of multi-phase materials could enhance catalytic performance for water electrolysis.