Redox-Active Octaiodophenoxy Cobalt Phthalocyanine for Elevating Oxygen Reduction Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Fuel cells and metal-air batteries rely on efficient oxygen reduction reaction (ORR) catalysts.
• Developing cost-effective, non-precious metal catalysts for ORR is crucial for sustainable energy.
• Phthalocyanine-metal complexes offer potential as ORR electrocatalysts due to their electronic properties.

Purpose of the Study:

• To design and synthesize a novel, earth-abundant, non-precious electrocatalyst for ORR.
• To investigate the ORR performance of octa-substituted 4-iodophenoxy cobalt(II) phthalocyanine (Co(II)OOIPc) and its hybrid with Ketjen black (KB).
• To evaluate the potential of the Co(II)OOIPc+KB hybrid as a durable and efficient catalyst for sustainable energy generation.

Main Methods:

• Synthesis of octa-substituted 4-iodophenoxy cobalt(II) phthalocyanine (Co(II)OOIPc).
• Fabrication and characterization of Co(II)OOIPc hybrid with Ketjen black (KB).
• Electrochemical evaluation of ORR activity using techniques like cyclic voltammetry and rotating disk electrode measurements in 0.1 M KOH.

Main Results:

• The optimized Co(II)OOIPc+KB hybrid catalyst exhibited a positive shift in onset potential (+0.878 V) and half-wave potential (+0.752 V vs RHE).
• The hybrid catalyst demonstrated enhanced ORR performance and durability compared to pristine Co(II)OOIPc, approaching benchmark Pt/C.
• The catalyst facilitated a 4-electron transfer pathway with a low Tafel slope (66 mV/dec) and high double-layer capacitance (10.57 mF cm⁻²).

Conclusions:

• The Co(II)OOIPc+KB hybrid catalyst is a cost-effective and efficient electrocatalyst for ORR.
• Synergistic effects between Co(II)OOIPc and KB, including π-π stacking and enhanced conductivity, contribute to improved performance.
• This durable and stable hybrid catalyst shows significant promise for sustainable energy generation applications.