Electrochemical Oxygen Reduction on Carbon Nitride

• Published in: ECS transactions Vol. 28; no. 23; pp. 11 - 26
• Main Authors: Lyth, Stephen M., Nabae, Yuta, Islam, Nazrul M., Kuroki, Shigeki, Kakimoto, Masa-aki, Ozaki, Jun-ichi, Miyata, Seizo
• Format: Journal Article
• Language: English
• Published: 08.10.2010
• ISSN: 1938-5862; 1938-6737
• DOI: 10.1149/1.3502333

Electrochemical oxygen reduction via non-precious, Fe-macrocycle-derived catalysts has potential to reduce the cost and increase acceptance of hydrogen-powered polymer electrolyte membrane fuel cells. However since these materials are a complex mixture of carbon, nitrogen and iron, the nature of the active site is still much debated. By using carbon nitride as an ideal, nitrogen-rich, iron-free catalyst we shed light on the role of carbon-nitrogen bonding in electrochemical oxygen reduction. Carbon nitride was synthesized on a carbon black support via a simple solvothermal process. The resulting material was pyrolyzed and characterized via a variety of techniques. Electrochemical testing revealed that carbon nitride pyrolyzed at 1000åC displayed the best oxygen reduction activity, with an onset potential of 0.90V and a low selectivity to H2O2 formation, indicating a 4-electron oxygen reduction pathway. The enhanced activity is attributed to enriched quaternary nitrogen in the material at this temperature, as confirmed by X-ray photoelectron spectroscopy.