Sustainable Bottom-Up Synthesis of Anisotropic Gold Nanoparticles

Anisotropic noble metal nanoparticles exhibit unique optical and catalytic properties that have the potential to revolutionize applications ranging from cancer therapy to hydrogen storage. While there is considerable drive for the commercial implementation of these materials, a significant barrier to industrial translation lies in the lack of rational synthetic methods to produce them. This gap introduces difficulties with both the reproducibility and the sustainability of anisotropic nanoparticle synthesis. Here, a robust approach for the solution-phase synthesis of gold nanoparticles of technological interest has been developed. Instead of using a seed template to access canonical gold nanomaterials such as nanorods and nanoprisms, a homogeneous nucleation approach has been developed where nucleation and growth occur in the same chemical environment. By regulating the stages of particle nucleation and growth, nanorods with lengths from 30 to 630 nm and triangular or hexagonal prisms with vertex-to-vertex lengths ranging from 120 to over 700 nm were produced in high yield. These results shed light on the factors that influence the growth of anisotropic nanomaterials, and allow for drastically more efficient synthetic routes. Specifically, this methodology allows for the reduction in the amount of reagents needed to synthesize nanorods and nanoprisms by as much as 90% by weight, and represent the first report of spectroscopically-discernible, colloidal gold nanoplates obtained using a seedless approach. Methods developed will facilitate future investigations concerning the formation of complex, hybrid nanoparticle architectures from anisotropic nanomaterial substrates