Effect of Molecular Adsorption on Metal Nanoparticles

M. M. MARISCAL; J. A. OLMOS ASAR; M. LUDUEÑA

Washington

Congreso; 11th Spring Meeting of the International Society of Electrochemistry; 2012

ISE

Colloidally prepared metal nanoparticles are gaining attention for catalytic applications because of the advanced possibilities to tailor their size and shape, which are often important factors governing catalytic activity and selectivity. In the case of bimetallic catalysts, composition is usually difficult to control by traditional techniques, but by colloidal chemistry the relative portions of the metals in the nanoparticles can be exactly predefined. This approach offers the advantage of controlling structure and composition of the resulting particles. Preparation, conservation and protection of metallic or multimetallic nanoparticles require protection 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 and small Au clusters , , 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 more 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 MD/MC codes. In particular we show the effect of soft and hard surfactant on the structure of gold nanoparticles of > 1nm. Finally, we will show very recent studies which involve the nucleation and growth processes of bimetallic NPs carried out in solution under control of the chemical potential of the metal ions.