Development of Novel Cube-Embedded MnO₂/ZnO Nanocomposite for OER Activity and Supercapacitor Performance Evaluation

The development of an inexpensive, efficient, and sustainable material suitable for energy storage applications is the need of modern era. Due to their affordability, eco-friendliness, high efficiency, and unique electronic structure metal oxides are the favorable candidate for this purpose. Here, the most desirable MnO₂/ZnO nanocomposites were fabricated via hydrothermal route. The successful fabrication of synthetic material was confirmed via X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscope, Raman spectroscopy, and X-ray photoelectron spectroscopy by analyzing the crystal structure, functionality, morphology, chemical property, and electronic properties. The electrochemical study was carried out in 1.0 M KOH (alkaline media) to assess the electrochemical performance of the fabricated composite materials for oxygen evolution reaction (OER) and supercapacitors. For this purpose, several various tests, like cyclic voltammetry, linear sweep voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy were performed. The electrochemical results revealed that the fabricated MnO₂/ZnO nanocomposite has a Tafel slope and overpotential of 33.7 mV dec⁻¹ and 274 mV, respectively. The small values of the Tafel slope and overpotential confirmed that our fabricated MnO₂/ZnO nanocomposite is a potential candidate for OER. Moreover, the resultant MnO₂/ZnO nanocomposite has a specific capacitance of 1038.3 F g⁻¹ and a power density of 396.3 Wh kg⁻¹. All these results confirmed that the fabricated MnO₂/ZnO nanocomposite is a potential candidate for energy storage applications.