MOF-derived dual metal (Fe, Ni) –nitrogen–doped carbon for synergistically enhanced oxygen reduction reaction

Abstract

Fe-N-C materials have been shown as promising non-precious electrocatalysts for oxygen reduction reaction (ORR), yet the activity as well as the durability in acidic electrolytes is still far from satisfactory. Herein, a dual metal (Fe, Ni)-nitrogen-doped carbon (FeNi-NC) was prepared by pyrolysis of Fe, Ni co-doped ZIF-8. The FeNi0.25-NC catalyst exhibits a comparable activity for the ORR to the commercial Pt/C catalyst, with the half-wave potential at 0.79 VRHE in HClO4 and 0.86 VRHE in NaOH electrolyte. Especially, FeNi0.25-NC shows excellent ORR activity in phosphorous acid electrolyte superior to the commercial Pt/C catalyst, owing to the excellent tolerance of the Fe, Ni active sites to phosphate anions. The systematic investigation manifests that Ni plays a double role in improving the ORR activity and stability of Fe-N-C. One side, Ni-N and Fe-N moieties synergistically boost the ORR especially in the high ORR overpotential region, and another side, Ni acts as a catalyst during the high temperature carbonization process to promote graphitization and increase the stability of the FeNi-N-C catalyst. It is demonstrated that the MOF-derived dual metal (Fe, Ni) -nitrogen-doped carbon catalyst (FeNi-NC) has a great potential application in both fuel cells and metal-air batteries. This work provides an effective dual-metal strategy in modulating both the activity and stability of the M-N-C catalysts for the ORR in acidic electrolytes.