Growth and physical-chemical characterization of manganese oxide and graphene-manganese oxide films for potential applications in energy store devices

Abstract

The need for progress in the development of energy supply devices such as batteries and large capacitors has led to the improvement and innovation of these devices so that they can store energy efficiently, and additionally, they must be small, light, with low production costs, and friendly to the environment. For these reasons, in this investigation results of the characterization of physical and chemical behaviors of graphene-manganese oxide and copper and manganese oxide-copper systems are studied. The graphene was synthesized through the electrochemical exfoliation technique and deposited as a film on common glass and silicon substrates via the spray technique, and over this film, Mn₂O₃ films were deposited through spin coating. The Raman results showed the presence of peaks D and G, located at 1534 and 1597 cm⁻¹, respectively. XPS analysis demonstrated that the graphene is made up of three layers. TEM studies determined that the graphene is polycrystalline, and XRD established the manganese oxide coatings’ growth along the (222) and (440) planes of Mn₂O₃. The optical behavior indicated that the absorbance of the graphene-Mn₂O₃ system decreases the energy gap in 0.8 eV concerning Mn₂O₃ films. The voltage-current measurements suggest that the density current in the discharge process of the Mn₂O₃–Cu electrode system was improved approximately 3-fold with the graphene-Mn₂O₃–Cu electrode system. The obtained results conclude that the addition of graphene to manganese oxide coatings increases their electrochemical performance, so graphene-manganese oxide could be used in energy storage devices.