Controlled Construction of Core-Shell Structured Prussian Blue Analogues towards Enhanced Oxygen Reduction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are promising electrocatalysts for oxygen reduction reaction (ORR).
• Traditional MOF synthesis requires high temperatures and often results in poor water stability, hindering industrial use.
• Developing robust and efficient MOF-based ORR catalysts is crucial for energy applications.

Purpose of the Study:

• To develop a facile low-temperature synthesis method for water-stable MOF electrocatalysts.
• To investigate the ORR performance of Mn and Fe co-loaded Prussian blue analogues with core-shell structures.
• To evaluate the potential of these novel catalysts in zinc-air batteries.

Main Methods:

• A low-temperature ion exchange method was employed to synthesize Mn and Fe co-loaded Prussian blue analogues.
• Core-shell structured frameworks were achieved with controlled Mn and Fe loading.
• Electrocatalytic performance for ORR was evaluated using rotating disk electrode (RDE) voltammetry.
• Performance in zinc-air batteries was assessed, including power density and long-term stability.

Main Results:

• The synthesized catalysts exhibited a core-shell structure with Mn concentrated in the outer shell.
• The optimal catalyst (HMPB-2.6Mn) demonstrated a high ORR half-wave potential of 0.86 V.
• The catalyst achieved a zinc-air battery power density of 119 mW cm⁻².
• Negligible degradation was observed over 60 hours of operation, comparable to commercial Pt/C.

Conclusions:

• A facile low-temperature ion exchange method successfully produced water-stable Mn and Fe co-loaded Prussian blue analogues.
• The core-shell structure and synergistic Mn-Fe interactions are key to the enhanced ORR activity and stability.
• These MOF-based electrocatalysts show significant potential for industrial application in energy conversion devices like zinc-air batteries.