Sandia National Laboratories, Albuquerque, NM 87185-1411, USA.
Phys Chem Chem Phys. 2012 Oct 14;14(38):13309-18. doi: 10.1039/c2cp41446e.
Producing nanostructures with high surface area that are stable is important to accomplish sustained use of catalytic materials in practical settings. Avoiding the processes of ripening and sintering that typically hinder stability has long been recognized as a significant challenge and much research is focused on addressing these issues. In this article, we investigate a Pt nanostructure-a holey nanosheet-that exhibits high surface area and stability. The findings from lattice gas simulations produce a stability diagram that relates a critical hole diameter to sheet thickness. The stability is now addressed from a thermodynamic point of view, and, in particular, the crucial role of curvature is considered. We find that the stability of certain sized holes is due to the near zero mean curvature of the surface of the holes and of the surrounding flat sheet. Molecular dynamics simulations of Pt (using an embedded atom potential) are reported for small nanoclusters and model holes in sheets to illustrate the strong effects of curvature on thermodynamic properties such as the lowering of melting and surface melting temperatures.
制备具有高表面积且稳定的纳米结构对于在实际环境中持续使用催化材料非常重要。长期以来，人们一直认识到避免通常会阻碍稳定性的熟化和烧结过程是一项重大挑战，因此许多研究都集中在解决这些问题上。在本文中，我们研究了一种具有高表面积和稳定性的 Pt 纳米结构——多孔纳米片。晶格气体模拟的结果生成了一个稳定性图，其中将临界孔直径与片厚度相关联。现在从热力学角度来解决稳定性问题，特别是考虑了曲率的关键作用。我们发现，某些尺寸的孔的稳定性是由于孔表面和周围平坦片的近零平均曲率所致。还报道了使用嵌入原子势的 Pt 分子动力学模拟，用于小纳米团簇和模型孔中的片，以说明曲率对热力学性质（例如降低熔点和表面熔化温度）的强烈影响。
