Edge-Functionalized Polyphthalocyanine Networks with High Oxygen Reduction Reaction Activity

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Two-dimensional (2D) conjugated aromatic networks (CAN) are crucial for energy applications.
• Developing efficient electrocatalysts for oxygen reduction reactions (ORR) is vital for clean energy technologies.

Purpose of the Study:

• To fabricate novel 2D CANs using a ball milling technique.
• To evaluate the electrocatalytic activity of these CANs for ORR and their performance in zinc-air batteries.

Main Methods:

• Fabrication of 2D CANs via ball milling of polymeric cobalt phthalocyanine precursors.
• Functionalization with aromatic acid anhydride substituents (tetraphenylphthalic anhydride).
• Characterization of material properties (layer thickness, surface area, active sites) and electrochemical testing.

Main Results:

• Optimal CANs exhibited uniform, thin layers (2.9 nm) with high BET surface area (92 m² g⁻¹).
• Well-defined and highly exposed Co-N₄ active sites were achieved.
• Electrocatalytic ORR activity was 44 mA mg⁻¹, outperforming Pt/C catalysts by 1.2-6.0 fold.
• Zinc-air batteries with these catalysts achieved high power densities (137 mW cm⁻² areal, 0.68 W mg⁻¹ mass).

Conclusions:

• The developed support-free and pyrolysis-free strategy offers a novel route for 2D material synthesis.
• These 2D CANs demonstrate excellent potential as efficient electrocatalysts for clean energy conversion and storage.