Carbon supported engineering NiCo2O4 hybrid nanofibers with enhanced electrocatalytic activity for oxygen reduction reaction

Abstract

The design of cheap and efficient oxygen reduction reaction (ORR) electrocatalysts is of a significant importance in sustainable and renewable energy technologies. Therefore, ORR catalysts with superb electrocatalytic activity and durability are becoming a necessity but still remain challenging. Herein, we report C/NiCo2O4 nanocomposite fibers fabricated by a straightforward electrospinning technique followed by a simple sintering process as a promising ORR electrocatalyst in alkaline condition. The mixed-valence oxide can offer numerous accessible active sites. In addition, the as-obtained C/NiCo2O4 hybrid reveals significantly remarkable electrocatalytic performance with a highly positive onset potential of 0.65 V, which is only 50 mV lower than that of commercially available Pt/C catalysts. The analyses indicate that C/NiCo2O4 catalyst can catalyze O2-molecules via direct four electron pathway in a similar behavior as commercial Pt/C catalysts dose. Compared to single NiCo2O4 and carbon free NiCo2O4, the C/NiCo2O4 hybrid displays higher ORR current and more positive half-wave potential. The incorporated carbon matrices are beneficial for fast electron transfer and can significantly impose an outstanding contribution to the electrocatalytic activity. Results indicate that the synthetic strategy hold a potential as efficient route to fabricate highly active nanostructures for practical use in energy technologies.