Multimetallic FeCoNiO_x Nanoparticles Covered with Nitrogen-Doped Graphene Layers as Trifunctional Catalysts for Hydrogen Evolution and Oxygen Reduction and Evolution

This Article demonstrates the synthesis and catalysis of a functional material with one core and dual shells containing an alloyed FeCoNi core covered with a thin layer of spinel oxides and encapsulated in nitrogen-doped graphene layers (FeCoNiOx@NG). The graphene shell is enriched with defects that play an important role in facilitating the catalytic process and reactant transport. This material shows highly trifunctional catalytic activity for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction in an alkaline electrolyte solution. The multifunctional catalytic activity is attributed to the catalyst’s multimetallic property. The thin layer of spinel oxides is enriched with oxygen vacancies that increase the catalytic activity for the oxygen evolution reaction and enhance the stability. The ORR activity and stability is comparable to that of 10% Pt/C, and the OER performance is comparable to that of Ir-black. An application of this functional material is explored. A zinc/air battery with FeCoNiOx@NG as the cathode catalyst is designed, assembled, and tested. The zinc/air battery exhibits a good rechargeable cycling performance, which corresponds to the excellent capability of OER/ORR catalytic cycles.