A high-performance catalyst based on binary CuFe alloyed nanocrystals encapsulated in nitrogen-doped graphene nanosheets towards oxygen reduction reaction

We successfully developed a hybrid catalyst based on binary CuFe alloy nanoparticles (NPs) uniformly encapsulated within nitrogen-doped graphene nanosheets (CuFe NPs/N-rGO). The catalyst displayed excellent performance for oxygen reduction in 0.1 M KOH medium. In this context, the catalyst showed an onset potential of +0.99 V (vs. RHE), which is comparable to that of Pt/C catalyst. The fast ORR kinetic was also confirmed with high electron transfer number of 3.8–3.88. In addition, the catalyst demonstrated the superior stability and methanol tolerance to commercial Pt/C product. The enhanced ORR performance of the CuFe NPs/N-rGO hybrid is assumed to an efficient synergistic effect between CuFe NPs and N-rGO nanosheets. In particular, the formation of encapsulation structure in which CuFe NPs are wrapped by several layers of N-rGO not only improves charge transfer but also effectively avoids from the dissolution and aggregation of the active metal NPs, thereby improving active sites, reaction kinetic, and stability of catalyst. The results suggest that the CuFe NPs/N-rGO hybrid may be a promising noble metal-free ORR catalyst for alkaline fuel cell applications.