Uniform nickel–cobalt nanoparticles embedded in nitrogen-doped carbon nanofibers for highly active and durable oxygen reduction electrocatalysts

Abstract

A proper design and ingenious preparation of advanced nonnoble metal catalysts with high cost performance and durability for the oxygen reduction reaction (ORR) is in great demand and still full of great challenges. In this study, nickel–cobalt bimetallic nanoparticles uniformly embedded in nitrogen-doped carbon nanofibers (NiCo@NCNFs) were fabricated via a facile electrospinning technique, followed by a carbonization process. The Ni–Co nanoparticles are highly dispersed and uniformly embedded in highly conductive nitrogen-doped carbon fibers, providing a high specific surface area (640.8 m² g⁻¹), abundantly exposed active sites and easily accessible electronic channels, thus achieving high ORR performance. In particular, the optimized Ni_0.5Co₁@NCNF catalyst exhibits a high onset potential (E_onset = 0.90 V vs. RHE) and half-wave potential (E_1/2 = 0.83 V vs. RHE) in an alkaline medium. Moreover, it possessed an extraordinary long-term stability and methanol tolerance in comparison to a commercial 20% Pt/C catalyst. This simple and cost-effective strategy provides a basis for the large-scale production of highly efficient catalysts that are used in numerous renewable energy systems.