3D nitrogen-doped graphene aerogel-supported Fe ₃O ₄ nanoparticles as efficient electrocatalysts for the oxygen reduction reaction

Three-dimensional (3D) N-doped graphene aerogel (N-GA)-supported Fe ₃O ₄ nanoparticles (Fe ₃O ₄/N-GAs) as efficient cathode catalysts for the oxygen reduction reaction (ORR) are reported. The graphene hybrids exhibit an interconnected macroporous framework of graphene sheets with uniform dispersion of Fe ₃O ₄ nanoparticles (NPs). In studying the effects of the carbon support on the Fe ₃O ₄ NPs for the ORR, we found that Fe ₃O ₄/N-GAs show a more positive onset potential, higher cathodic density, lower H ₂O ₂ yield, and higher electron transfer number for the ORR in alkaline media than Fe ₃O ₄ NPs supported on N-doped carbon black or N-doped graphene sheets, highlighting the importance of the 3D macropores and high specific surface area of the GA support for improving the ORR performance. Furthermore, Fe ₃O ₄/N-GAs show better durability than the commercial Pt/C catalyst.