吉林大学李达团队报道了电子辐照下过渡金属二硫化物纳米带缩窄成纳米线的原因。相关研究成果发表在2024年11月26日出版的国际知名学术期刊《美国化学会杂志》。

过渡金属二硫化物（TMDC）纳米线因其真实的亚纳米宽度（<1 nm）和本征金属性，在1D电子通道、自旋电子学、光电子和催化中具有实际应用。尽管在TMDC纳米线的合成中经常观察到TMDC纳米带在电子照射下变窄为纳米线，但这种意想不到的结构转变背后的机制仍然是一个谜。

该文中，为了揭示潜在的机制，研究人员将第一性原理计算与1D纳米线的全局结构搜索相结合，并表明由于边缘-边缘相互作用，宽度小于6环的1H相MoS₂纳米带与其纳米线对应物相比在能量上是不利的。电子辐照下S缺陷引起的弯曲效应是MoS₂纳米带转变为纳米线的主要驱动力。

研究认为，Mo₆S₆纳米线的前体是一种定义明确的Mo₁₁S₁₁-i纳米线，其化学计量比出乎意料。固有的局部压缩应变触发了从Mo₁₁S_11-i到其略微改性的姊妹纳米线Mo₁₁S_11-ii的相变，其特征是构型（Mo₁S₁）₅和Mo₆S₆。

在电子辐照的触发下，纳米带经历了一个逐步变窄的过程，在每一步中顺序剥离Mo₁S₁片段，形成坚固的Mo₆S₆纳米线。这种独特的窄化机制对于其他TMDC在电子照射下的纳米带到纳米线的转变具有普遍性。

该研究强调了迄今为止尚未探索的制造单个M₆X₆纳米线的机制，并有助于深入了解TMDC纳米带在电子照射下的变窄现象。

附：英文原文

Title: Why Does a Transition Metal Dichalcogenide Nanoribbon Narrow into a Nanowire under Electron Irradiation

Author: Yue Liu, Tian Cui, Da Li

Issue&Volume: November 26, 2024

Abstract: Transition metal dichalcogenide (TMDC) nanowires have practical applications in 1D electron channels, spintronics, optoelectronics, and catalysis due to their authentic subnanometer width (<1 nm) and intrinsic metallicity. Although narrowing of a TMDC nanoribbon into a nanowire under electron irradiation has been frequently observed in the synthesis of TMDC nanowires, the mechanism underlying this unexpected structural transformation remains a mystery. Here, to reveal the underlying mechanism, we combine first-principles calculations with a global structure search of 1D nanowires and show that a nanoribbon of 1H-phase MoS2 with a width narrower than 6 rings is energetically unfavorable compared with its nanowire counterpart due to the edge–edge interaction. The bending effect induced by S defects under electron irradiation is the major driving force for the transition of MoS2 nanoribbon into a nanowire. We predict that the precursor of the Mo6S6 nanowire is a well-defined Mo11S11-i nanowire with an unexpected stoichiometry. The intrinsic local compressive strain triggers a phase transition from Mo11S11-i to its slightly modified sister nanowire, Mo11S11-ii, which is characterized by the configuration (Mo1S1)5&Mo6S6. Triggered by electron irradiation, the nanoribbon undergoes a step-by-step narrowing process with sequential peeling of a Mo1S1 fragment in each step to form a robust Mo6S6 nanowire. This unique narrowing mechanism is universal for the nanoribbon-to-nanowire transformation of other TMDCs under electron irradiation. Our study highlights a hitherto unexplored mechanism for creating individual M6X6 nanowires and contributes to an in-depth understanding of the narrowing of TMDC nanoribbons under electron irradiation.

DOI: 10.1021/jacs.4c12428

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c12428