Modeling free and surfactant-protected metal nanoparticles

OLMOS-ASAR, J.; LUDUEÑA, M.; SPITALE, A.; MARISCAL, M. M.

Congreso; XX International Materials Research Congress; 2011

Metallic nanoparticles are perhaps one of the most outstanding applications of nanotechnology due to potential use of these nanostructures on diverse fields, i.e. biosensors, catalysis, drug “delivery” and construction of nano-circuits. Preparation, conservation and protection of metallic nanoparticles require passivation with organic ligand molecules if they will remains in a colloidal suspension. When nanoparticles are made of gold, a relatively easy way of protect them is through organic molecular self-assembly, particularly with thiols molecules due to the strong interaction between sulfur and gold atoms. Self-assembly monolayer’s (SAM’s) have been intensively studied, at experimental and theoretical level, on extended gold (111) surfaces. Nevertheless, a clear understanding about some fundamental structural aspects of passivated Au nanoparticles in the range of 1-10 nm still does not exist. In the present talk we show the application of a new semiempirical potential recently developed in our Lab to describe molecule-metal interfaces in a realistic way. Using Density Functional calculations (DFT) in combination with the bond-order concept we have developed a new semiempirical framework which is very simple and easy to implement in standard molecular dynamics codes. In particular we show the effect of soft and hard surfactant on the structure of gold nanoparticles. Finally, we will show very recent studies which involve the nucleation and growth processes of bimetallicl NP´s carried out in solution under control of the chemical potential of the metal ions.