Structural, morphological, and electrocatalytic investigations of Fe3O4-doped Mn3O4 composite supported on carbonaceous materials derived from chitosan for oxygen reduction reaction

Abstract

To substitute the present precious metal-based catalysts for oxygen reduction reactions (ORRs), developing highly efficient, durable, and stable electrocatalysts that achieve high current generation with low overpotentials is a challenging task. In this work, a hybrid ternary Fe₃O₄–Mn₃O₄/C composite was synthesized via a simple and cost-effective co-precipitation method and employed as the cathode material for ORR in methanol-based fuel cells. Fe₃O₄ and Mn₃O₄ supported on carbonaceous materials derived from chitosan were also prepared for comparison. The synthesized products were thoroughly characterized using powder X-ray diffraction (pXRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) mapping for understanding the structure, morphology, and composition of the composite. It was evident that the ternary hybrid composite Fe₃O₄–Mn₃O₄/C possessed a well-defined oxygen reduction peak centered at −0.578 V in the presence of O₂ in 0.5 M KOH electrolyte for ORR activity. The tolerance of Fe₃O₄–Mn₃O₄/C nanocomposite was verified by inoculating 0.5 M CH₃OH, which resulted in the nanocomposite being unsusceptible to methanol crossover. Thus, the synthesized ternary composite could be considered a promising electrocatalyst for improving ORR performance in fuel cells.