Controlling shape and spatial organization of silver crystals by site-selective chemical growth method for improving surface enhanced Raman scattering activity

A novel approach for a controlled growth of pattern-directed organization of Ag nanocrystals (NCs) onto rigid substrate has been proposed to achieve large-scale functional materials. A soft nanoporous template was used to create first a hexagonal array of gold nanoparticles by a seed-mediated growth colloidal process. The size and morphology of the Ag NCs were then controlled by a site-selective heterogeneous nucleation and growth onto the Au precursors. While removing the nanoporous polymer mask before the growth process leads to the formation of Ag flower-shape crystals, keeping this thin polymer mask rather leads to the formation of sheet-like structures. The growth mechanism of the template-directed synthesis of Ag crystals arrays was investigated. In addition, the optical properties of Ag NCs arrays were discussed in relation to their morphology and organization. Finally, this facile and simple multistep approach is particularly attractive due to its environmentally gentle processing conditions and represents an open pathway to several technologically large-scale nanomaterials fabrication such as hierarchically ordered crystal architectures for sensor applications. (C) 2015 Elsevier B.V. All rights reserved.