Encapsulating metal organic framework into hollow mesoporous carbon sphere as efficient oxygen bifunctional...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer rich metal nodes and high surface area for electrochemical applications.
• Poor electrical conductivity and ion transport limit MOFs' effectiveness as electrocatalysts.
• Developing advanced MOF-based materials is crucial for next-generation energy storage and conversion systems.

Purpose of the Study:

• To develop a facile in situ growth method for synthesizing MOFs@hollow mesoporous carbon spheres (HMCS) yolk-shell structured hybrid materials.
• To investigate the structural, electrical, and catalytic properties of the synthesized ZIF@HMCS hybrid material.
• To evaluate the performance of the ZIF@HMCS hybrid material as an air electrode in rechargeable Zn-air batteries.

Main Methods:

• Facile in situ growth method for synthesizing MOFs@HMCS yolk-shell structured hybrid material.
• Characterization of the hybrid material's structure, morphology, and electrochemical properties.
• Electrochemical testing for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity.
• Fabrication and testing of a rechargeable Zn-air battery utilizing the hybrid material as an air electrode.

Main Results:

• The ZIF@HMCS hybrid material demonstrated controlled encapsulation of Zeolitic Imidazolate Framework-67 (ZIF-67) within hollow mesoporous carbon spheres.
• Significantly enhanced electrical conductivity and ion transport of ZIF-67 within the yolk-shell structure.
• Superior oxygen reduction reaction (ORR) activity (0.823 V vs RHE half-wave potential, 13.8 mA cm⁻² kinetic current density) surpassing commercial Pt/C.
• Excellent oxygen evolution reaction (OER) performance with an overpotential of 407 mV at 10 mA cm⁻².
• High power density (120.2 mW cm⁻²) and long-term stability (80 h) in rechargeable Zn-air batteries.

Conclusions:

• The MOFs@HMCS yolk-shell design effectively addresses the conductivity and ion transport limitations of MOFs.
• The synthesized ZIF@HMCS material shows exceptional electrocatalytic activity for both ORR and OER.
• This hybrid material presents a promising air electrode for high-performance rechargeable Zn-air batteries.
• The MOFs@HMCS yolk-shell strategy offers a versatile platform for developing MOF-based electrocatalysts.