Controllable Synthesis of 3D Thorny Plasmonic Gold Nanostructures and Their Tunable Optical Properties

Three-dimensional (3D) thorny plasmonic gold nanostructures were synthesized by adding Ag nanospheres to the reaction systems containing HAuCl4 and NH2OH at room temperature. The redox displacement between silver seeds and HAuCl4 first yielded gold nanoseeds, and the simultaneously formed byproduct AgCl precipitates controlled the growth of the produced gold nanoseeds on the basis of the surface-catalyzed reduction of AuCl4- by NH2OH. When the total amount of the reactants was fixed, the morphology of thorny gold nanostructures could be easily controlled via changing the volume of the reaction system, the reaction temperature, or the manner of introducing the growth solution, all of which altered the reaction rate and consequently the crystal growth pathway of final products. The resulting gold nanostructures exhibited a distinctive surface plasmon resonance band in the visible and near-IR region depending on their morphologies, which could be readily controlled by varying the experimental parameters. This study opens a new route for fabricating metal nanoparticles with designed optical and structural properties.