Thermal decomposition behavior and computational analysis of alpha and beta manganese dioxide nanorods

Abstract

The thermal stability of materials directly influences their applications. This present work investigates the difference of thermal decomposition behaviors of alpha (α) and beta (β) manganese dioxide (MnO2) nanorods. Differential scanning calorimeter coupled with thermogravimetric analysis is conducted to find the difference of thermal process. The X-ray diffraction analysis and scanning electron microscope are employed to test crystal structures and morphologies at various roasted temperatures, respectively. The activation energy and Debye temperature are calculated to explain the difference in the decomposition process. It is found that β-MnO2 can be fully converted to Mn2O3 after roasting at 650 °C, whereas only part of α-MnO2 has changed. Besides, the β-MnO2 nanorods go through a continuous thinning from room temperature to 500 °C, while the morphology of α-MnO2 remains the same until it reaches over 300 °C. These results suggest that α-MnO2 nanorods have better thermal resistance than β-MnO2, which could facilitate the selection of thermal stable materials for electrochemistry industries and energy materials application.