Achieving High-Temperature Stability of Metastable α-MoC_1-x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

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_1−x by mounting zinc atoms into its lattice structure. Such a structural construction could suppress the phase transformation from α-MoC_1−x to β-Mo₂C through restricting the displacement of Mo atoms upon increased temperature. The resultant metastable α-MoC_1−x can be stabilized up to 1000 °C and this stability temperature is the highest for the metastable α-MoC_1−x so far. Synchrotron X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) confirm the structure of Zn-mounted α-MoC_1−x. Density functional theory (DFT) calculations reveal that the introduction of the Zn atoms in the lattice structure of α-MoC_1−x could significantly decrease the energy difference (ΔE) between α-MoC_1−x and β-Mo₂C, thus effectively suppressing the phase transformation from α-MoC_1−x to β-Mo₂C and accordingly maintaining the high-temperature stability of α-MoC_1−x. This novel strategy can be used as a universal method to be extended to synthesize metastable α-MoC_1−x 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.