Hierarchical Flaky Spinel Structure with Al and Mn Co-Doping Towards Preferable Oxygen Evolution Performance

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Water electrolysis is a crucial clean energy technology for hydrogen production.
• The oxygen evolution reaction (OER) is a rate-limiting step, necessitating advanced catalysts.
• Developing efficient and stable anode OER catalysts is essential for improving electrolyzer performance.

Purpose of the Study:

• To synthesize and characterize a novel bimetallic (Al, Mn) co-doped nanoporous spinel cobalt iron oxide (np-CFO) as a high-performance OER catalyst.
• To investigate the structural, compositional, and electrochemical properties of the synthesized catalyst.
• To evaluate the catalyst's efficiency and durability for hydrogen production via water electrolysis.

Main Methods:

• A two-step dealloying strategy was employed to synthesize the nanoporous spinel CoFe2O4 (np-CFO).
• The catalyst's hierarchical flaky configuration with nanosheets on micron-sized flakes was characterized.
• Electrochemical performance was assessed through OER overpotential, Tafel slope, and long-term durability tests under various conditions.

Main Results:

• The optimized np-CFO (Al, Mn) catalyst exhibited a low OER overpotential of 320 mV at 10 mA cm⁻² and a Tafel slope of 45.09 mV dec⁻¹.
• The catalyst demonstrated exceptional durability, maintaining stability for ~100 h at 500 mA cm⁻² under harsh conditions (6 M KOH, 60 °C).
• Theoretical simulations confirmed that Al and Mn co-doping optimize the electronic structure, reducing the OER energy barrier to 1.35 eV.

Conclusions:

• The developed bimetallic co-doped nanoporous CFO is a highly efficient and stable OER catalyst.
• The hierarchical nanostructure enhances active sites and mass transport, contributing to superior catalytic activity.
• This work provides a practical and scalable approach for synthesizing advanced OER catalysts for clean hydrogen production.