The exceptional electrocatalytic performance of the 1T phase of MoS in the hydrogen evolution reaction has motivated researchers to design methods for enhancing the stability of this phase. Herein, the electronic origin of the stability of 1T-MoS and its distorted phases: 1T' (zig-zag), 1T′′ (diamond chain), and 1T′′′ (triangle) was elucidated using first-principles calculations. The phase stability can be altered by the repeating MoS units that play a significant role in the generation of metal clusters. A novel skew trapezoidal bipyriamidal (STB) distortion was observed in the MoS unit, which increased the stability of the distorted 1T phases in MoS. The highly distorted STB unit was found in the stable 1T' phase with an enhanced orbital population. The short edges of the distorted STB increase the electron density fraction of the Mo atoms, promoting Mo-Mo bond formation. The 1T' phase exhibited superior stability due to stronger electron delocalization in the Mo-Mo bond compared to that in the 1T′′ and 1T′′′ phases. The nature of Mo-Mo bonding varied on different metal clusters for 1T' (σ, π, and δ), 1T′′ (π and σ), and 1T′′′ (σ) bond types. Therefore, the stability of the 1T'-MoS phase depends on the extent of distortion in the MoS unit, Mo-Mo bond nature, and layer thickness.

中文翻译：

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MoS6单元中的斜梯形双锥体畸变稳定了1T-MoS2单层的畸变相

MoS2的1T相在析氢反应中优异的电催化性能促使研究人员设计提高该相稳定性的方法。在此，利用第一性原理计算阐明了 1T-MoS 稳定性的电子起源及其扭曲相：1T'（锯齿形）、1T''（菱形链）和 1T'''（三角形）。重复的 MoS 单元可以改变相稳定性，这些单元在金属簇的生成中发挥着重要作用。在MoS2单元中观察到一种新的斜梯形双锥体（STB）畸变，这增加了MoS2中畸变1T相的稳定性。高度扭曲的 STB 单元被发现处于稳定的 1T' 阶段，轨道布居增强。扭曲的STB的短边增加了Mo原子的电子密度分数，促进Mo-Mo键的形成。与 1T” 和 1T”” 相相比，由于 Mo-Mo 键中电子离域更强，1T' 相表现出优异的稳定性。对于 1T'（σ、π 和 δ）、1T''（π 和 σ）和 1T'''（σ）键类型，Mo-Mo 键合的性质在不同金属簇上有所不同。因此，1T'-MoS相的稳定性取决于MoS单元的变形程度、Mo-Mo键性质和层厚度。