Design and fabrication for platinum-free oxygen reduction reaction catalysts

Hydrogen energy is a candidate for a new alternative energy system because hydrogen molecules can be generated from various resources, stored, and transported. Although hydrogen-energy-harnessing polymer electrolyte fuel cells (PEFCs) have been expected, they have not yet been widely used. Platinum, an oxygen reduction reaction (ORR) catalyst, is an expensive and non-abundant resource, and it has poor durability for ORR activity. Therefore, metal-free carbon nanomaterials have been developed as alternative platinum catalysts. Nitrogen-doped carbon nanomaterials have been reported to exhibit especially high ORR catalytic activity. However, the ORR mechanism has not been clarified. To achieve highly efficient ORR activity, doping nitrogen species should be precisely controlled in the carbon framework. In this study, we try to dope nitrogen atoms to carbon nanomaterials via a fluorination–defluorination process to clarify the mechanism of ORR catalytic activity.