Microwave assisted synthesis of Mn ₃O ₄ nanograins intercalated into reduced graphene oxide layers as cathode material for alternative clean power generation energy device

Abstract

Mn ₃O ₄ nanograins incorporated into reduced graphene oxide as a nanocomposite electrocatalyst have been synthesized via one-step, facile, and single-pot microwave-assisted hydrothermal technique. The nanocomposites were employed as cathode material of fuel cells for oxygen reduction reaction (ORR). The synthesized product was thoroughly studied by using important characterization, such as XRD for the structure analysis and FESEM and TEM analyses to assess the morphological structures of the material. Raman spectra were employed to study the GO, rGO bands and formation of Mn ₃O ₄@rGO nanocomposite. FTIR and UV–Vis spectroscopic analysis were used to verify the effective synthesis of the desired electrocatalyst. The Mn ₃O ₄@rGO-10% nanocomposite with 10 wt% of graphene oxide was used to alter the shiny surface of the working electrode and applied for ORR in O ₂ purged 0.5 M KOH electrolyte solution. The Mn ₃O ₄@rGO-10% nanocomposite electrocatalyst exhibited outstanding performance with an improved current of − 0.738 mA/cm ² and shifted overpotential values of − 0.345 V when compared to other controlled electrodes, including the conventionally used Pt/C catalyst generally used for ORR activity. The tolerance of Mn ₃O ₄@rGO-10% nanocomposite was tested by injecting a higher concentration of methanol, i.e., 0.5 M, and found unsusceptible by methanol crossover. The stability test of the synthesized electrocatalyst after 3000 s was also considered, and it demonstrated excellent current retention of 98% compared to commercially available Pt/C electrocatalyst. The synthesized nanocomposite material could be regarded as an effective and Pt-free electrocatalyst for practical ORR that meets the requirement of low cost, facile fabrication, and adequate stability.