Core‐shell FeCo N‐doped biocarbons as stable electrocatalysts for oxygen reduction reaction in fuel cells

Summary A facile route is described for the synthesis of FeCo alloys encapsulated in the N‐doped hierarchical carbon shells (denoted as Fe x Co 100‐x @N‐doped C) by using a combined hydrothermal carbonization of cellulose and NH 3 microwave ammoxidation. Various spectroscopic measurements are used to characterize the physicochemical properties of Fe x Co 100‐x @N‐doped C samples and their activity as well as stability in the oxygen reduction reaction (ORR) are investigated in alkaline electrolytes. The Fe x Co 100‐x @N‐doped C samples exhibit the core FeCo bimetals alloying with N (verified by X‐ray absorption spectroscopy [XAS] and transmission electron microscopy) and N‐doped onto highly porous carbons in the shell (proofed by N 2 adsorption‐desorption isotherms and X‐ray photoelectron spectroscopy [XPS]). Among the Fe x Co 100‐x @N‐doped C catalysts, the Fe 50 Co 50 @N‐doped C with an atomic alloy ratio of FeCo (1:1) has a higher ORR performance ( E onset = −0.05 V vs Ag/AgCl) and a surpassing durability (via a 4‐electron ORR route) in comparison to other Fe x Co 100‐x @N‐doped C and commercial Pt/C catalysts. By XAS and XPS, the formation of Fe‐N in the inner core and pyridinic‐N on outer shell may be responsible for the superior ORR performance of Fe 50 Co 50 @N‐doped C catalysts. These biomass‐derived carbon composites with unique core‐shell FeCoN@N‐doped porous carbon structure prepared by using a time and energy saving microwave‐assisted method could offer a possible cathodic electrode in fuel cell applications.