Structural Insights into Multi-Metal Spinel Oxide Nanoparticles for Boosting Oxygen Reduction Electrocatalysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Multi-metal oxides (MMOs) offer tunable properties for catalysis but their complex nature hinders understanding.
• Spinel structures with multiple metal sites present additional challenges in correlating structure to electrocatalytic activity.

Purpose of the Study:

• To systematically investigate the elemental contributions to structural flexibility in Mn-Co-Fe spinel oxides.
• To elucidate the origin of enhanced electrocatalytic activity for the oxygen reduction reaction (ORR).

Main Methods:

• Synthesis of uniform-sized multi-metal spinel oxide nanoparticles.
• Comprehensive characterization of crystal and electronic structures.
• Electrochemical testing and computational studies.

Main Results:

• Cobalt incorporation optimizes site occupancy and modifies electronic states of active manganese sites.
• The optimized Co0.25Mn0.75Fe2.0-MMO catalyst achieved a high half-wave potential of 0.904 V (vs RHE).
• Exceptional mass activity of 46.9 A goxide-1 at 0.9 V (vs RHE) with good stability was demonstrated.

Conclusions:

• Elemental composition and site occupancy critically influence the ORR performance of spinel MMOs.
• This work provides fundamental insights into designing highly active and stable MMO electrocatalysts.