Self-assembly of gold nanoparticles prepared with 3,4-ethylenedioxythiophene as reductant

3,4-Ethylenedioxythiophene (EDOT) was used as the reductant for the first time in the preparation of gold nanoparticles by the reduction of HAuCl4 in THF solution with alkylamine as the stabilizer. During the reduction process of HAuCl4, EDOT was oxidized and oxidatively polymerized. The alkylamine stabilizer and the produced polymer (PEDOT) played a very important role in the subsequent self-assembly of the gold nanoparticles. With trioctylamine as the stabilizer, uniform spherical aggregates (with a diameter of ca. 230 nm) of gold nanoparticles (with a size of ca. 10 nm) were formed. The samples were characterized by TEM, EDS, XRD, XPS, FT-IR, UV-vis, and electrochemical cyclic voltammetry (CV) measurements. The pi-pi interaction between the PEDOT coated on the gold nanoparticles was considered to be the driving force for the formation of such aggregates. More interestingly, hollow spherical aggregates composed of smaller gold nanoparticles were observed when higher concentrations of EDOT and trioctylamine were used in the reactive solution. Homogeneous spherical nanoparticles which could self-assemble into an ordered structure were also prepared when dioctylamine was used as the stabilizer. The results indicate that the aggregation states and the morphology of the gold nanoparticles are controllable through changing the concentration of EDOT and trioctylamine or selecting other akylamines as the stabilizer.