An approach for selectively oxidizing spherical nanoparticles in polydispersion gold nanorods

A new approach is developed to selectively oxidize spherical gold nanoparticles and thus leads to gold nanorods with a narrow size distribution in the polydispersity gold nanorods solution prepared by seed-mediated synthesis methodology. It is found that in the medium of cetyltrimethylammonium bromide (CTAB) and NaH2PO4 solution, the fraction of spherical gold nanoparticles can be significantly reduced, as evidenced by the intensity decrease of absorption band at around 520 nm of the solution and temporal evolution of the nanoparicle TEM images. In addition, continuous flow of air through the polydispersity gold nanorods solution proves to be able to enhance the oxidation rate of spherical particles dramatically.