Nanoreactor\nof Fe, N Co-Doped Hollow Carbon Spheres\nfor Oxygen Reduction Catalysis

Abstract

A simple template strategy was applied to prepare a Fe,\nN co-doped\nhollow carbon (Fe-NHC) nanoreactor for the oxygen reduction reaction\n(ORR) by coating Fe nanoparticles (Fe-NPs) with polydopamine (PDA),\nfollowed by high temperature pyrolysis and acid-leaching. With this\nmethod, Fe-NPs were used as both the template and the metal precursor,\nso that the nanoreactors can preserve the original spherical morphology\nand embed Fe single atoms on the inner walls. The carbonized PDA contained\nabundant N content, offering an ideal coordination environment for\nFe atoms. By regulating the mass ratio of Fe-NPs and PDA, an optimal\nsample with a carbon layer thickness of 12 nm (Fe-NHC-3) was obtained.\nThe hollow spherical structure of the nanoreactors and the atomically\ndispersed Fe were verified by various physical characterizations.\nAs a result, Fe-NHC-3 performed well in ORR tests under alkaline conditions,\nwith high catalytic activity, durability, and methanol resistance,\ndemonstrating that the as-fabricated materials have the potential\nto be applied in the cathodic catalysis of fuel cells.