Fabrication of facet-controlled au nanostructures via seed-mediated growth

Abstract

As nanostructures are widely used in various fields, interest in methodologies for nanostructures has also increased. In particular, the attainment of a uniform nanostructure is considered important, given the decisive influence of shape of nanostructure on the chemical and physical properties of the nanomaterials. In this study, the fabrication of two-dimensional (2D) faceted gold (Au) nanoarrays and the synthesis of three-dimensional (3D) Au nanocrystals are successfully achieved with seed-mediated growth method. In Chapter 2, a novel Au nanostructure design is presented. The application of dewetting to a lithography-fabricated Au planar nanoarray induced a transformative process to a hemispherical particle array. Subsequently, the faceting procedure was executed on the exposed surface of the Au nanoarray, leading to the formation of the {111} plane and facilitated by polyvinylpyrrolidone (PVP). For the application of the controllable faceted-2D Au nanoarray, Chapter 3 provides a systemic study on the growth solution environment to control the exposed surface. Hexadecyltrimethylammonium chloride (CTAC) and ascorbic acid were used as surfactant and reducing agent, respectively, and bromide and iodide were used as additives, for the growth environment. It was confirmed that growth rate control and facet-selective adsorption of halide ions were key factors, and polyhedral Au nanoparticles with low-index facets were synthesized through precise adjustment of the relevant factors. This study presents an effective strategy to form facet-controlled Au nanostructures in both two and three dimensions.