Gao Cheng, Meng Tao, Yang Pei, Guo Wei, Cao Minhua
Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China.
Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, P. R. China.
Chem Asian J. 2019 Jun 3;14(11):1977-1984. doi: 10.1002/asia.201900312. Epub 2019 Apr 16.
Despite a significant advancement in preparing metastable materials, one common problem is the strict and precious reaction conditions due to their metastable structures. Herein, we achieved the preparation of high-temperature stabilized metastable α-MoC by mounting zinc atoms into its lattice structure. Such a structural construction could suppress the phase transformation from α-MoC to β-Mo C through restricting the displacement of Mo atoms upon increased temperature. The resultant metastable α-MoC can be stabilized up to 1000 °C and this stability temperature is the highest for the metastable α-MoC so far. Synchrotron X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) confirm the structure of Zn-mounted α-MoC . Density functional theory (DFT) calculations reveal that the introduction of the Zn atoms in the lattice structure of α-MoC could significantly decrease the energy difference (ΔE) between α-MoC and β-Mo C, thus effectively suppressing the phase transformation from α-MoC to β-Mo C and accordingly maintaining the high-temperature stability of α-MoC . This novel strategy can be used as a universal method to be extended to synthesize metastable α-MoC from different precursors or other mounted elements. Moreover, the optimal product exhibits excellent lithium storage performances in terms of the cycling stability and rate performance.
尽管在制备亚稳材料方面取得了显著进展，但由于其亚稳结构，一个常见的问题是反应条件严格且苛刻。在此，我们通过将锌原子嵌入其晶格结构实现了高温稳定的亚稳α-MoC的制备。这种结构构建可以通过限制温度升高时Mo原子的位移来抑制α-MoC向β-Mo₂C的相变。所得的亚稳α-MoC在高达1000 °C的温度下仍能保持稳定，且该稳定温度是迄今为止亚稳α-MoC的最高温度。同步辐射X射线吸收光谱（XAS）和X射线光电子能谱（XPS）证实了嵌入锌的α-MoC的结构。密度泛函理论（DFT）计算表明，在α-MoC的晶格结构中引入锌原子可以显著降低α-MoC与β-Mo₂C之间的能量差（ΔE），从而有效抑制α-MoC向β-Mo₂C的相变，进而维持α-MoC的高温稳定性。这种新策略可作为一种通用方法扩展到从不同前驱体或其他嵌入元素合成亚稳α-MoC。此外，最佳产物在循环稳定性和倍率性能方面表现出优异的锂存储性能。
