Effect of Cationic Surfactants with Different Counterions on the Growth of Au Nanoclusters.

The influence of a series of cationic surfactants composed of cetyltrimethylammonium cations with different counterions (Br- , Cl- , OH- , C7 H8 O3 S- , [CeCl3 Br]- , and NO3 - ) on the aging process of gold nanoclusters (Au NCs) was studied. The finely different points of Au NCs treated by different surfactants were demonstrated by UV-vis and fluorescence spectra, transmission electron microscopy images, etc. Because of the difference of counterions, these surfactants have diverse physicochemical properties in surface activity, specific conductivity, pH, and viscosity, which may account for the difference of Au NCs in the aging process. In addition, the affinity of the counterions in surfactants to the surface of Au has also been demonstrated completely. This affinity may further guide the difference of the synthesized Au nanomaterials.