Mechanistic analysis of the ORR
 

Oxygen reduction reaction (ORR) is one of the most studied reactions in the electrocatalysis. The most abundant element oxygen is used as the oxidizing agent in the low-temperature hydrogen fuel cells. Typically, platinum-based catalysts have been used to improve the ORR kinetics, limiting large-scale commercialization of fuel cells for energy applications.  Understanding the ORR mechanism and the active sites information on the NPGM or metal-free catalysts are the real bottlenecks for the development of highly active and durable Pt-free catalysts for the ORR. Despite the series of attempts to characterize the active sites and ORR mechanism, the conclusions are not clear and lead to debate.

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Dr. Muthukrishnan’s group is working on fundamental aspects of ORR, characterizing the active sites and mechanism of the Fe-N/C and N-doped carbon catalysts, via the kinetic analysis. A bottom-up approach to describe the role of various possible entities present in the heat-treated heteroatom doped Fe-containing catalysts is individually studied. The iron oxide on porous carbon support for its role in ORR was studied.  Also, the mechanism of the synergistic effect on the two heteroatom-doped (boron and nitrogen) metal-free carbon catalysts. To specific, the BCN materials are studied, and its kinetic analysis reveals the mechanism of the synergistic effect.

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The defects on the carbon substrates towards ORR activity are analyzing by specially created defects. The selective edge functionalization of heteroatom-doped graphene was employed to create the topological defects, which significantly improves the ORR activity in alkaline medium. (highlighted in figure)

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