Spinel CoMn2O4 nanoparticles supported on a nitrogen and phosphorus dual doped graphene aerogel as efficient electrocatalysts for the oxygen reduction reaction

Abstract

In this work, we present a novel hybrid composed of spinel CoMn₂O₄ nanoparticles and a N, P dual-doped graphene aerogel (CoMn₂O₄/NPGA). The CoMn₂O₄/NPGA is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of the CoMn₂O₄/NPGA composite towards the ORR was assessed using a linear sweep voltammetry method. Rotating disk electrode (RDE) measurements show that the as-obtained CoMn₂O₄/NPGA shows excellent ORR activity in an alkaline medium comparable to the benchmark Pt/C catalyst. Electrochemical measurements reveal that the ORR on CoMn₂O₄/NPGA proceeds through an almost four-electron pathway. Simultaneously, the methanol tolerance and operational stability of CoMn₂O₄/NPGA toward the ORR are prominently higher than those of commercial Pt/C. All these conspicuous properties suggest that our proposed CoMn₂O₄/NPGA may be used as a prospective Pt-free catalyst in alkaline direct methanol fuel cells.