A Sustainable Approach to the Preparation of MoO2 Quantum Dots and the Pseudocapacitive Performance before and after Calcination

Sustainability

Liexing Zhou¹  Yi Xia¹  Yi An²  Dong Fang²  Weizhi Gong²  Cheng Pan²  Junli Wang²  Mingjun Wang²  Jianlin Liu³ 

[1] Analytic and Testing Research Center of Yunnan, Kunming 650093, China;Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China;Faculty of Science, Shaoyang University, Shaoyang 422000, China;

关键词: MoO₂ quantum dots;    surfactants;    calcination;    MoO₃;    intercalation pseudocapacitance;   

DOI  :  10.3390/su14094880

来源: DOAJ

【 摘 要 】

The present preparation methods of molybdenum dioxide (MoO₂) quantum dots (QDs) are often cumbersome and not environmentally friendly, and more importantly, the prepared MoO₂ QDs are usually wrapped in surfactants, which are difficult to be removed and impact their intrinsic characterization and performance. Herein, we present a facile, scalable and sustainable approach to obtain clean and pure MoO₂ QDs (1.5~3 nm), which consists of a hydrothermal reaction and a further calcination process in vacuum following freeze drying. Furthermore, the influence of calcination temperature, atmosphere and time is also studied. The calcination at 400 °C for 2 h in vacuum can efficiently remove the surfactants wrapping on the MoO₂ QDs without obvious size change, whereas the calcination in nitrogen will lead to a slight increase in size, and the calcination in air could transform MoO₂ QDs into MoO₃ nanoplates. In addition, the pseudocapacitive performance of the as-prepared samples is tested and compared by electrochemical methods, and the specific capacitance of the clean MoO₂ QDs is about 1.4 times larger than that of MoO₂ QDs with surfactants at 5 mV s⁻¹. This study also demonstrates a possible way to efficiently remove the organic substance wrapping on quantum dot materials.

【 授权许可】

Unknown