Investigation of pH Effect on Gold Nanorod Synthesis

Gold nanorods (GNRs) are routinely prepared by the seed-mediated growth method under the assistant of surfactant CTAB and it is important to understand the factors that control the formation process of GNRs. Here we investigated systematically how the pH conditions contribute to the GNR morphology and size evolution with UV-Vis absorption spectrometry and TEM. It was found that the aspect ratio and morphology of GNRs are dependent on the pH of the growth solution. Moreover, the GNR growth pathway also varies at different pH. Our results indicated that pH affected CTAB micelle's stability and reduced its absorption ability on gold surface, which changes the gold atom deposition behavior onto the surface.