A cobalt-nitrogen complex on N-doped three-dimensional graphene framework as a highly efficient electrocatalyst for...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Platinum's high cost and scarcity limit its use as an oxygen reduction reaction (ORR) electrocatalyst in fuel cells.
• Alternative catalysts using earth-abundant metals like iron (Fe) or cobalt (Co) with nitrogen on carbon supports show promise for reducing costs without sacrificing performance.

Purpose of the Study:

• To develop a cost-effective and high-performance electrocatalyst for the oxygen reduction reaction (ORR).
• To investigate the potential of pyrolyzed vitamin B12 on reduced graphene as an ORR electrocatalyst for alkaline fuel cells.

Main Methods:

• Synthesized a novel electrocatalyst by pyrolyzing the corrin structure of vitamin B12 on a simultaneously reduced graphene support (g-VB12).
• Evaluated the electrocatalyst's performance for the oxygen reduction reaction (ORR) in alkaline media, assessing half-wave potential, selectivity, and durability through electrochemical cycling.

Main Results:

• The g-VB12 electrocatalyst exhibited a highly positive half-wave potential, with only a ~30 mV deviation from platinum/carbon (Pt/C).
• Achieved high selectivity for the ORR, indicated by an electron transfer number close to 4.
• Demonstrated excellent durability, with only an 11 mV shift in half-wave potential after 10,000 potential cycles.
• The catalyst's performance is attributed to the homogeneous distribution of cobalt-nitrogen (Co-Nx) active sites and the mesoporous structure of the nitrogen-doped graphene support.

Conclusions:

• The low-cost g-VB12 electrocatalyst shows high activity and long-term stability for the oxygen reduction reaction (ORR).
• This material is a promising alternative to platinum-based catalysts for applications in alkaline fuel cells.