MnO 2 nanostructures: A review of synthesis methods and multifunctional applications

Abstract

Manganese dioxide (MnO₂) nanorods have emerged as a promising class of one-dimensional nanomaterials due to their excellent electrochemical properties, high surface area, and structural tunability. These characteristics make MnO₂ nanorods highly suitable for applications in energy storage, catalysis, environmental remediation, and the biomedical field. The synthesis of MnO₂ nanorods plays a crucial role in determining their properties, and various methods have been developed to tailor their size, morphology, and crystallinity. Common synthesis methods include hydrothermal and sol-gel techniques, which offer controlled growth conditions and high crystallinity. The microemulsion method is another widely used approach due to its simplicity and cost-effectiveness. Additionally, microwave-assisted synthesis and low-temperature synthesis methods provide rapid and efficient routes for obtaining MnO₂ nanorods with the desired properties. Each method influences the phase composition, porosity, and surface characteristics, which in turn affect their performance in different applications. MnO₂ nanorods find extensive use in energy storage devices, such as supercapacitors and lithium-ion batteries, where their high surface area and redox activity enhance charge storage capacity. In catalysis, they serve as effective catalysts in oxidation reactions and environmental remediation processes, including wastewater treatment and pollutant degradation. Furthermore, their applications extend to biosensors, where their electrochemical activity improves the detection of biomolecules, and to biomedical fields, such as drug delivery and antibacterial agents. This paper provides an overview of various synthesis methods for MnO₂ nanorods and highlights their diverse applications. Understanding the relationship between synthesis techniques and material properties is key to optimizing their performance in advanced technologies.