A thermodynamic perspective of the metastability of holey sheets: the role of curvature

作者：van Swol Frank^*; Challa Sivakumar R; Shelnutt John A

来源：Physical Chemistry Chemical Physics, 2012, 14(38): 13309-13318.

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.

• 出版日期2012