Molecular Dynamics Simulations of Thermally Induced Surface and Shape Evolution of Concave Au Nanocubes: Implications for Catalysis,ACS Applied Nano Materials

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Molecular Dynamics Simulations of Thermally Induced Surface and Shape Evolution of Concave Au Nanocubes: Implications for Catalysis
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2021-08-23 , DOI: 10.1021/acsanm.1c01994
Yu-Hua Wen ₁ , Lei Li ₁ , Ya-Meng Li ₁ , Tao Zhao ₁ , Rao Huang ₁

Affiliation

High-index faceted concave nanoparticles have drawn widespread attention over the past few years because of their exceptional properties and promising applications. Their surface structures, especially steps, sharp corners, and edges, could serve as highly active sites to boost the catalytic activity and selectivity. In this work, we systematically investigated surface and shape evolutions of concave Au nanocubes, respectively, bounded with {210}, {310}, and {410} high-index facets during heating by molecular dynamics simulations. Convex Au nanocubes enclosed by these facets were also addressed for comparison. Our results demonstrated that the concave nanocubes possessed significantly higher fractions of surface atoms and remarkably lower averaged coordination numbers than the convex ones. Although the melting points of all the nanocubes were approximately equal, independent of their surface structures, the thermal stability of the surface and shape of the concave nanocubes was markedly inferior to that of the convex ones. The critical temperature of shape transformation follows the order of {210} < {310} < {410} in the concave nanocubes, while the reverse order was observed in the convex nanocubes. Our work suggests that there should be a selective compromise between high fractions of low-coordinated surface atoms and the stable surface structure for applications of concave nanoparticles. This work extends the fundamental understanding about the temperature-dependent surface structure of metallic nanoparticles with high-index facets, and provides a theoretical reference for enhancing their thermodynamic stability.

中文翻译：

凹面金纳米立方体的热诱导表面和形状演变的分子动力学模拟：对催化的影响

过去几年，高指数刻面凹面纳米粒子因其卓越的性能和广阔的应用前景而受到广泛关注。它们的表面结构，尤其是台阶、尖角和边缘，可以作为高活性位点来提高催化活性和选择性。在这项工作中，我们通过分子动力学模拟系统地研究了在加热过程中分别与 {210}、{310} 和 {410} 高折射率面结合的凹面 Au 纳米立方体的表面和形状演变。还处理了被这些面包围的凸面 Au 纳米立方体以进行比较。我们的结果表明，凹面纳米立方体比凸面纳米立方体具有显着更高的表面原子分数和显着更低的平均配位数。尽管所有纳米立方体的熔点大致相等，但与其表面结构无关，但凹形纳米立方体的表面和形状的热稳定性明显低于凸形纳米立方体。形状转变的临界温度在凹纳米立方体中遵循 {210} < {310} < {410} 的顺序，而在凸纳米立方体中观察到相反的顺序。我们的工作表明，对于凹形纳米粒子的应用，应该在高比例的低配位表面原子和稳定的表面结构之间进行选择性折衷。这项工作扩展了对具有高指数小平面的金属纳米粒子的温度依赖性表面结构的基本理解，并为提高其热力学稳定性提供了理论参考。

更新日期：2021-09-24

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