Fuel Cell Cathode Catalyst with Heme-Like Structure Formed from Nitrogen of Glycine and Iron

Abstract

It is known that heme is closely related to chemical reactions involving oxygen, especially cathodic oxygen reduction, and that carbon materials with an Fe–N4Fe–N4 moiety mimicking the heme center and embedded on the surface function as cathode catalysts for fuel cells, which would be one of the promising candidates for precious-metal-free catalysts and would lead to the realization of the widespread use of fuel cells. In this study, we found that a heat-treatment of a mixture of Fe(II) lactate, glucose, and glycine, which is the starting material of heme biosynthesis, generated a carbon material with the Fe–N4Fe–N4 moiety by self-organization of Fe and N from glycine during pyrolysis. A polymer electrolyte fuel cell formed using the carbon material in the cathode generated electricity, confirming its function as the cathode catalyst, although the performance was inferior to that of a conventional Pt-based fuel cell. However, the increase in the structural regularity caused by an increase in the glycine content in the starting mixture improved the activity and durability.