Manganese Oxide Nanoparticles: An Insight into Structure, Synthesis and Applications

Manganese oxide nanoparticles with different crystal phases, morphologies, and structural diversity along with their exceptional properties like high specific surface area, a high fraction of surface atoms, non-toxic nature, and excellent redox properties are drawing attention for various applications in storage science, especially in the batteries, super-capacitors, energy conversion, and the environmental catalysis field. Precise control of particle size, morphology, surface area, Mn_x⁺ oxidation state, etc. is the utmost important aspect to explore their application to the full potential. Here, the emphasis is on the recent trends in manganese oxide research – structure, synthesis, and applications. The structure of numerous crystalline phases of manganese oxide nanoparticles are summerized and several facile chemical synthesis processes to achieve the desired crystalline/amorphous structure are discoursed. Temperature and different synthesis conditions dependent phase transformations of β-MnO₂, α-Mn₂O₃, and Mn₃O₄ from α-MnO₂ are discussed as well. The pragmatic approach directs that the application field is mostly controlled by the morphologies.