Enhanced Oxygen Reduction Reaction on Fe/N/C Catalyst in Acetate Buffer Electrolyte

Non-precious metal catalysts (NPMCs) have gained significant attention over the past decade as realistic alternatives to platinum-based catalysts for the oxygen reduction reaction (ORR) in fuel cells. An interesting feature of NPMCs is that the active site can be regarded as a 2D structure where both sides influence the catalytic process. Such a 2D structure enables different possibilities to alter the active site through the specific chemical environment as compared with typical 3D materials such as Pt based catalysts. In this work, we focus on the effect of carboxylate buffer species in the vicinity of iron–nitrogen-carbon (Fe/N/C) catalytic sites. The catalytic interface is studied with respect to the ORR activity using the rotating disk electrode (RDE) in aqueous electrolyte as well as theoretical modeling using density functional theory (DFT) calculations. We find that the ORR activity on Fe/N/C catalyst is promoted by carboxyl species in general and increases 4-fold in acetate buffer as compared to 0.1 M aqueous HClO4 electrolyte.