AI 中文总结
本研究通过大规模反应分子动力学模拟揭示Janus MXene纳米卷形成机制及颗粒封装行为，发现其层间距可调控，但封装时释放的H₂气体可能缩短电池寿命，为MXene基储能电极设计提供参考。
AI 中文摘要
将二维Janus MXene的形貌转变为纳米卷可解锁其独特性能。尽管已通过实验验证了可规模化合成路线，但纳米卷形成的原子级机制仍知之甚少。我们采用大规模反应分子动力学模拟，结合密度泛函理论（DFT）以及实验结构与弹性质进行验证，研究三种Janus MXene（(Tx)Ti₂C(Ty)，其中(Tx)和(Ty)分别表示底层和顶层表面终止基团，包括裸露(-b)、-O和-OH）的稳定性，并量化控制纳米卷形成的驱动力与几何参数。我们模拟了长度范围为10 nm至120 nm以上的方形及无限宽薄片，发现1%至7%的晶格诱导应变会在这些结构中产生弯曲力矩；薄片会根据产生的曲率和初始尺寸发生卷曲、弯曲或形成纳米管。对于初始长度为120 nm的MXene，(O)Ti₂C(OH)和(b)Ti₂C(OH)会形成多层纳米卷，层间距约为0.7 nm，内径约为7 nm；而(b)Ti₂C(O)则产生大得多的层间距（约1.7 nm）和超过20 nm的内径。我们还表明，在锚定纳米颗粒存在时，Janus MXene的自发卷曲会形成核-壳复合材料，其中颗粒会使纳米卷局部变形并加宽层间通道；这种局部可调的扩大层间距为基于MXene的储能电极提供了有前景的设计途径。不过，我们的模拟显示封装过程中会释放H₂气体，这会促进纳米气泡形成，可能缩短电池寿命。
英文摘要
Morphology transfer of 2D Janus MXenes into nanoscrolls unlocks unusual properties. Although a scalable synthesis route has been experimentally verified, the atomistic mechanism underlying nanoscroll formation remains poorly understood. We use large-scale reactive molecular dynamics simulations, validated against density functional theory (DFT) and experimental structural and elastic properties, to investigate stability and quantify the driving forces and geometry governing nanoscroll formation in three Janus MXenes, (Tx)Ti2C(Ty), where (Tx) and (Ty) denote the bottom and top surface terminations among bare (-b), -O, and -OH. Both square and infinitely wide flakes with lengths ranging from 10 to over 120 nm are simulated. We find that 1-7% lattice-induced strain generates a bending moment in these structures. The sheet scrolls, curves, or forms a nanotube depending on the resulting curvature and initial sheet size. For MXenes with an initial length of 120 nm, multiwalled nanoscrolls form with interlayer distances of around 0.7 nm and inner diameters of about 7 nm for (O)Ti2C(OH) and (b)Ti2C(OH), whereas (b)Ti2C(O) instead produces a much larger interlayer distance of around 1.7 nm and an inner diameter exceeding 20 nm. We show that spontaneous scrolling of a Janus MXene in the presence of an anchored nanoparticle produces a core@shell composite, in which the particle locally deforms the nanoscroll and widens the interlayer channels. This locally tunable, enlarged interlayer spacing offers a promising design route for MXene-based energy-storage electrodes. However, our simulations reveal H2 gas release during encapsulation, which promotes nanobubble formation that can reduce battery life.
CommentsThis is a preprint submitted to a journal for publication
