title: Efficient seed-mediated method for the large-scale synthesis of Au nanorods.
abstract: Seed-mediated methods are widely followed for the synthesis of Au nanorods (NRs). However, mostly dilute concentrations of the Au precursor (HAuCl4) are used in the growth solution, which leads to a low final concentration of NRs. Attempts of increasing the concentration of NRs by simply increasing the concentration of HAuCl4, other reagents in the growth solution and seeds lead to a faster growth kinetics which is not favourable for NR growth. Herein, we demonstrate that the increase in growth kinetics for high concentrations of reagents in growth solution can be neutralised by decreasing the pH of the solution. The synthesis of the NRs can be scaled up by using higher concentrations of reagents and adding an optimum concentration of HCl in the growth solution. The concentration of HAuCl4in the growth solution can be increased up to 5 mM, and 10-20 times more NRs can be synthesised for the same reaction volume compared to that of the conventional seed-mediated method. We have also noticed that a cetyltrimethylammonium bromide (CTAB)-to-HAuCl4molar ratio of 50 is sufficient for obtaining high yield of NRs.
authors.affiliation: Department of Physics, COMSATS Institute of Information Technology, Park Road, Islamabad, 44000 Pakistan.|Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
authors.forename: Waqqar
authors.initials: W
authors.lastname: Ahmed
authors.affiliation: Department of Physics, COMSATS Institute of Information Technology, Park Road, Islamabad, 44000 Pakistan.
authors.forename: Arshad Saleem
authors.initials: AS
authors.lastname: Bhatti
authors.affiliation: Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
authors.forename: Jan M
authors.initials: JM
authors.lastname: van Ruitenbeek
keywords: Gold nanoparticles; Large-scale synthesis; Plasmonics; Seeded protocol