Influence of Capping Ligands on the Self-organization of Gold Nanoparticles into Superlattices from CTAB Reverse Micelles

摘要

Gold nanoparticles with size 3-10 nm (diameter) were prepared by the reduction of HAuCl_4 in a CTAB/octane + 1-butanol/H_2O reverse micelle system using NaBH_4 as the reducing agent. The as-formed gold nanoparticle colloid was characterized by UV/vis absorption spectrum and transmission electron microscopy (TEM). Various capping ligands, such as alkyl-thiols with different chain length and shape, trioctylphosphine (TOP), and pyridine are used to passivate the gold nanoparticles for the purpose of self-organization into superstructures. It is shown that the ligands have a great influence on the self-organization of gold nanoparticles into super-lattices, and do-decanethiol C_(12)H_(25)SH is confirmed to be the best ligand for the serf-organization. Self-organization of C_(12)H_(25)SH-capped gold nanoparticles into 1D, 2D and 3D superlattices has been observed on the carbon-coated copper grid by TEM without using any selective precipitation process.