Reviewed by Lexie CornerOct 18 2024
A group of researchers from the Jinling Institute of Technology in China, led by Yuan Zhao, explored the potential of an Fe-N-C catalyst with dual nitrogen sources. The findings revealed that the Fe-N-C catalyst could surpass Pt-based catalysts in several critical performance areas. This research was published in Frontiers in Energy.
While metal-air batteries and fuel cells are regarded as future clean energy technologies, their efficiency hinges on the oxygen reduction reaction (ORR). Historically, platinum (Pt) and its alloys have been the preferred catalysts for this reaction due to their high activity, but they are hindered by poor stability and high costs.
The Search for Pt-Free Alternatives
The team’s innovative approach involved developing an Fe-N-C catalyst that enhances the distribution density of active catalytic sites by incorporating two nitrogen sources: polyaniline (PANI) and dicyandiamide (DCDA).
These nitrogen sources improve the material's morphology and structure, increasing its effectiveness in driving the oxygen reduction reaction (ORR). The new catalyst boosts overall activity by ensuring a higher availability of catalytic sites, maintaining a high nitrogen-pyrrole/nitrogen-graphitic (N-P/N-G) ratio.
We found that the dual nitrogen sources played a complementary role. While PANI generated a coarser carbon structure with dominant micropores, DCDA produced a finer, more graphitized material. Together, they created a catalyst with enhanced surface area and improved catalytic performance.
Yuan Zhao, Jinling Institute of Technology
Promising Results in the Lab
The outcomes were remarkable. Electrochemical tests showed that the new Fe-N-C catalyst outperformed commercial Pt/C catalysts in the oxygen reduction reaction ORR.
One of the most notable features of the Fe-N-C catalyst is its stability. In alkaline media, it exhibited excellent durability, maintaining performance over time. Additionally, it demonstrated higher resistance to methanol, a common fuel impurity that can degrade the performance of Pt-based catalysts.
The dual nitrogen sources allowed us to fine-tune the catalyst's structure in ways that hadn't been fully explored before. We saw significant improvements in both the surface area and the activity of the catalyst.
Rongrong Hu, Study Co-Author, Nanjing University of Science and Technology
The Future of Fe-N-C Catalysts
The development of this Fe-N-C catalyst represents a major advancement in the hunt for platinum-free ORR substitutes. With its improved activity, stability, and methanol resistance, the new catalyst holds promise for applications in fuel cells and metal-air batteries.
Zhao added, “While our results are promising, there is still more work to be done. We are now exploring how different metal elements and nitrogen sources can further improve the performance of Fe-N-C catalysts. Our ultimate goal is to create a catalyst that is not only high-performing but also scalable and cost-effective.”
Journal Reference:
Zhao, Y. et. al. (2024) Oxygen reduction reaction performance of Fe-N-C catalyst with dual nitrogen source. Frontiers in Energy. doi.org/10.1007/s11708-024-0956-2