A phase transformation route to porous 2D Mn3O4 nanosheets is developed by heat treatment of exfoliated layered MnO2 nanosheets. The calcination of MnO2 nanosheets at an elevated temperature of ≥ 500 °C in Ar atmosphere leads to the formation of porous 2D nanosheets as well as to reductive phase transition to low-valent Mn3O4. The formation of spinel-structured Mn3O4 phase with mixed tetrahedral and octahedral local symmetries is obviously evidenced by micro-Raman and X-ray absorption spectroscopies. An elevation of heating temperature enlarges the surface pore of 2D nanosheet and lowers the average oxidation state of Mn ion. In comparison with Mn3O4 crystal, the porous 2D Mn3O4 nanosheets show higher electrode activities for lithium ion batteries (LIBs) with larger discharge capacities, better rate characteristics, and excellent cyclabilities, emphasizing the advantage of porous 2D nanosheet morphology in optimizing the electrode functionality of metal oxide. The present study underscores the validity of the present phase transformation route in exploring novel high-performance metal oxide–based LIB electrode materials.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF-2017R1A2A1A17069463) and by the Korea government (MSIT) (No. NRF-2017R1A5A1015365). The experiments at PAL were supported in part by MOST and POSTECH.
© 2019, Qatar University and Springer Nature Switzerland AG.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Waste Management and Disposal
- Ceramics and Composites