Iron and nitrogen co-modified multi-walled carbon nanotubes for efficient electrocatalytic oxygen reduction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Multi-walled carbon nanotubes (MWCNTs) are excellent supports for oxygen reduction reaction (ORR) catalysts due to their conductivity and surface area.
• Iron and nitrogen doping can improve MWCNT ORR activity but often require complex synthesis.
• Developing simpler methods for doping MWCNTs is crucial for practical applications.

Purpose of the Study:

• To engineer and synthesize iron and nitrogen co-modified multi-walled carbon nanotubes (Fe-N-MWCNTs) using a straightforward method.
• To investigate the synergistic effects of hierarchical nanostructure, high surface area, low resistivity, and intensified charge density on ORR activity.
• To evaluate the performance of the synthesized Fe-N-MWCNTs as electrocatalysts for ORR.

Main Methods:

• A simple two-step pyrolysis approach was employed to synthesize Fe-N-MWCNTs.
• Characterization of the synthesized materials focused on nanostructure, surface area, and electrical properties.
• Electrochemical performance for ORR was assessed in a 0.1 M KOH medium, comparing against a benchmark Pt/C electrocatalyst.

Main Results:

• The synthesized Fe-N-MWCNTs possess a hierarchical nanostructure, large specific surface area, and low resistivity.
• Enhanced charge density near the Fermi level was observed, contributing to superior ORR activity.
• The optimal Fe-N-MWCNTs achieved an onset potential of 0.92 V and a half-wave potential (E1/2) of 0.85 V, surpassing the Pt/C benchmark (E1/2 = 0.84 V).

Conclusions:

• A simple calcination process effectively modifies MWCNT supports for ORR electrocatalysis.
• Fe-N-MWCNTs demonstrate excellent ORR activity, making them a promising alternative to traditional catalysts.
• This strategy offers a feasible route for preparing cost-efficient and high-performance ORR electrocatalysts.