Abstract Diffusion of water across surfaces generally involves motion on an uneven and vibrating but otherwise stationary substrate. Based on molecular dynamics simulations, we study the diffusion behavior of water nanodroplets on the compressed phosphorene at different temperatures. The compression is applied in three different ways: equal biaxial compression, uniaxial compression along armchair and zigzag directions As the compressive strain increases, the diffusion coefficients are first reduced and then increased in all three cases at T = 300 K. When the compressive strain exceeds 1.6 % , the diffusion coefficient grows the fastest for the case of equal biaxial compression. As the temperature increases, two different modes are observed at the lower strain level ( ⩽ 1.4 % ) and relatively higher strain level ( ⩾ 1.4 % ). In the regime of lower level of strain, the diffusion coefficient exhibits an oscillating trend as the temperature increases. In the regime of higher level of strain, the diffusion coefficient increases linearly as the temperature increases. The fastest diffusion occurs under the equal biaxial compressive loading at the strain level of 2.4 % and temperature T = 340 K. The different diffusion behaviors of water nanodroplets are found to be related to the surface morphologies of phosphorene under compression, as well as friction coefficient and diffusion energy barrier of water molecules. Our results show that compressive deformation of phosphorene and temperature are important to control the dynamics of water molecules on the phosphorene. The phenomena reported here enrich the knowledge of molecular mechanisms for nanofluidic systems, and may inspire more applications with phosphorene and other 2D materials.

中文翻译：

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水纳米液滴在磷烯上的各向异性扩散：预压缩变形和温度的影响

摘要 水在表面上的扩散通常涉及在不平坦且振动但静止的基底上的运动。基于分子动力学模拟，我们研究了水纳米液滴在不同温度下在压缩磷烯上的扩散行为。以三种不同的方式施加压缩：等双轴压缩、沿扶手椅和之字形方向的单轴压缩随着压缩应变的增加，在 T = 300 K 时，所有三种情况下的扩散系数首先减小然后增加。当压缩应变超过1.6 % , 等双轴压缩时扩散系数增长最快。随着温度的升高，在较低的应变水平 (⩽ 1.4 % ) 和相对较高的应变水平 ( ⩾ 1.4 % ) 下观察到两种不同的模式。在较低应变水平的情况下，扩散系数随着温度的升高呈现振荡趋势。在较高应变水平的情况下，扩散系数随着温度的增加而线性增加。最快的扩散发生在应变水平为 2.4 % 和温度 T = 340 K 的等双轴压缩载荷下。 发现水纳米液滴的不同扩散行为与压缩下磷烯的表面形貌以及摩擦系数有关和水分子的扩散能垒。我们的结果表明，磷烯的压缩变形和温度对于控制磷烯上水分子的动力学很重要。这里报道的现象丰富了纳米流体系统分子机制的知识，