二维材料曲面生长:力学与化学的邂逅

2D materials growth on curved surfaces—when mechanics meets chemistry

理解二维材料在曲面上的生长形态和机制具有重要的理论和应用价值,但现有关于二维材料曲面生长的力学行为及形貌演化规律的研究极为缺乏。二维材料曲面生长会导致薄膜变形及其相关的应力/应变。这类应力可引发二维材料的滑移、屈曲、褶皱、断裂和离面运动等二次力学行为,并直接与生长反应耦合,进而改变材料的生长过程。与化学能和表面扩散主导的平面生长不同,曲面生长二维材料的形貌受曲面几何形状和材料力学行为的共同影响,会产生更为复杂多样的生长形貌。通过总结国际上相关研究进展,剖析了模拟曲面生长二维材料所面临的科学问题,并论述了如何结合原子模拟(如分子动力学和蒙特卡罗模拟)与唯象理论(如相场方法)开展多尺度计算研究,再辅以实验揭示二维材料曲面生长规律。

Understanding the growth mechanism of two-dimensional (2D) materials on curved surfaces is vital to both fundamental and applied study.However,very few reports have been found on describing mechanical behaviors and morphological evolution of 2D materials grown on curved surfaces.In fact,thegrowth of 2D materials on curved surfaces unavoidably incur structural deformations and lattice stress/strains.These will further cause intriguing mechanical phenomena such as slipping,buckling,wrinkling and cracking,which ultimately influence the growth kinetics of materials by coupling to chemical reactions at growth fronts.Different from the growth of 2D materials on a plane surface which is dominated by chemical energies and surface diffusions,the growth on curved surfaces is tied to surface geometries of substrates and mechanical properties of the materials,providing the room to form a rich variety of complex morphologies.By reviewing recent research progress in related fields,we analyze key challenges in simulating the growth of 2D materials on curved surfaces.We then suggest potential routes to addressing the challenges by performing a multiscale study through combining atomistic computations (i.e.molecular dynamics and Monte Carlo simulations) and phenomenological approaches (i.e.phase-field method),so as to reveal the growth mechanism of 2D materials on curved surfaces.