He Hanna, Li Xiaolong, Huang Dan, Luan Jinyi, Liu Sailin, Pang Wei Kong, Sun Dan, Tang Yougen, Zhou Wenzheng, He Lirong, Zhang Chuhong, Wang Haiyan, Guo Zaiping
State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, P. R. China.
Institute for Superconducting & Electronic Materials, School of Mechanical, Materials, Mechatronics, and Biomedical Engineering, University of Wollongong, Wollongong 2500, New South Wales, Australia.
ACS Nano. 2021 May 25;15(5):8896-8906. doi: 10.1021/acsnano.1c01518. Epub 2021 May 10.
Phase transition engineering, with the ability to alter the electronic structure and physicochemical properties of materials, has been widely used to achieve the thermodynamically unstable metallic phase MoS (1T-MoS), although the complex operating conditions and low yield of previous strategies make the large-scale fabrication of 1T-MoS a big challenge. Herein, we report a facile electron injection strategy for phase transition engineering and fabricate a composite of conductive TiO chemically bonded to 1T-MoS nanoflowers (TiO-1T-MoS NFs) on a large scale. The underlying mechanism analysis reveals that electron-injection-engineering triggers a reorganization of the Mo 4d orbitals and results in a 100% phase transition of MoS from 2H to 1T. In the TiO-1T-MoS NFs composite, the 1T-MoS demonstrates a higher electronic conductivity, a lower Na diffusion barrier, and a more restricted S release than 2H-MoS. In addition, conductive TiO bonding successfully resolves the stability challenge of the 1T phase. These merits endow TiO-1T-MoS NFs electrodes with an excellent rate capability (650/288 mAh g at 50/20 000 mA g, respectively) and an outstanding cyclability (501 mAh g at 1000 mA g after 700 cycles) in sodium ion batteries. Such an improvement signifies that this facile and scalable phase-transition engineering combined with a deep mechanism analysis offers an important reference for designing advanced materials for various applications.
相变工程能够改变材料的电子结构和物理化学性质，已被广泛用于制备热力学不稳定的金属相二硫化钼（1T-MoS），尽管先前策略的复杂操作条件和低产率使得大规模制备1T-MoS成为一项重大挑战。在此，我们报道了一种用于相变工程的简便电子注入策略，并大规模制备了化学键合到1T-MoS纳米花上的导电TiO复合材料（TiO-1T-MoS NFs）。潜在机理分析表明，电子注入工程引发了Mo 4d轨道的重新排列，并导致MoS从2H相到1T相的100%相变。在TiO-1T-MoS NFs复合材料中，与2H-MoS相比，1T-MoS表现出更高的电子导电性、更低的Na扩散势垒和更受限的S释放。此外，导电TiO键合成功解决了1T相的稳定性挑战。这些优点赋予TiO-1T-MoS NFs电极在钠离子电池中优异的倍率性能（在50/20000 mA g下分别为650/288 mAh g）和出色的循环稳定性（在1000 mA g下循环700次后为501 mAh g）。这种改进表明，这种简便且可扩展的相变工程与深入的机理分析相结合，为设计用于各种应用的先进材料提供了重要参考。
