Microwave assisted synthesis of Mn3O4 nanograins intercalated into reduced graphene oxide layers as cathode material for alternative clean power generation energy device

Abstract

Mn3O4 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 Mn3O4@rGO nanocomposite. FTIR and UV–Vis spectroscopic analysis were used to verify the effective synthesis of the desired electrocatalyst. The Mn3O4@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 O2 purged 0.5 M KOH electrolyte solution. The Mn3O4@rGO-10% nanocomposite electrocatalyst exhibited outstanding performance with an improved current of − 0.738 mA/cm2 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 Mn3O4@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.

Dynamics of reduced graphene oxide: synthesis and structural models

“…23 Hence, microwave-assisted thermal reduction of GO is a strategy to accelerate thermal reduction since energy is transferred directly to reagents. 2,145,173 In this method, reduction is triggered by both heating effect, and differences in the dielectric constants of GO and the solvent, which induces an instant increase in internal temperature, consequently, causing reduction. 2,145,179 Hence, selection of an appropriate solvent system for the microwave reduction of GO is critical in this regard.…”

“…For illustration, microwave-assisted hydrothermal methods are advantageous than either microwave or hydrothermal approaches in that the combination accelerates heating, effects a more sensitive reaction, and facilitates uniform heating. 173 The g-irradiation has also been reported recently as a facile, green, cost-effective method for RGO production (Table 4). 177 In the presence of water or alcohol, g-rays create H c (reductive) and OH c species (oxidative) due to water radiolysis.…”

“…For illustration, microwave-assisted hydrothermal methods are advantageous than either microwave or hydrothermal approaches in that the combination accelerates heating, effects a more sensitive reaction, and facilitates uniform heating. 173 …”

A comprehensive review on tungsten oxide nanostructures‐based electrochromic supercapacitors and machine learning models for design and process parameter optimization

“…These devices undergo a color change upon applying an appropriate potential, which can be reversed by reversing the applied potential, allowing for reversion to its initial state 23 . Supercapacitors and electrochromic devices have many aspects in common such as materials used, chemicals used, structural design, operating mechanisms, and so forth 17,24,25 . In other words, we can say that electrochromic supercapacitors are transparent electrochemical energy storage devices.…”

“…23 Supercapacitors and electrochromic devices have many aspects in common such as materials used, chemicals used, structural design, operating mechanisms, and so forth. 17,24,25 In other words, we can say that electrochromic supercapacitors are transparent electrochemical energy storage devices. The charging and discharging processes of a supercapacitor are similar to the coloration/bleaching processes that happen in an electrochromic device.…”