Two-step seed-mediated growth for the reproducible synthesis of high quality gold nanorods

Gold nanorods, as a type of anisotropic nanoparticles, require uniformity for their properties and applications. Here, we demonstrate the successful preparation of well-dispersed and uniformly shaped GNRs through a two-step seed-mediated growth method by separating the symmetry breaking of seeds from subsequent growth. We determined that adding the first growth solution (Solution A) into the second growth solution (Solution B) after 30 min was optimal, and monitored the growth progress by recording the growth status every 30 min, observing that the growth of Solution A (150 min) and Solution B (210 min) essentially ceased. Furthermore, by adjusting the seed quantity, silver ion content, and pH value of the growth solution in each step, we could tune the wavelength of the localized surface plasmon resonance (LSPR) peak within the range of 668 to 1020 nm. Additionally, the trend of overall electric field intensity variations were determined through finite difference time domain (FDTD) simulations. We believe that this approach will further facilitate practical applications of GNRs research, as these applications rely on the high uniformity of GNRs. Graphical abstract Synopsis . We demonstrate the preparation of uniformly shaped gold nanorods through a two-step seed-mediated growth method by separating the symmetry breaking of seeds from subsequent growth. By adjusting the seed quantity, Ag + content, and pH value of the growth solution, we could tune the LSPR from 668 to 1020 nm.