Large-area arrays of epitaxially aligned silver nanotriangles seeded by gold nanostructures

Abstract

The ability to separate nucleation and growth processes into distinct steps has proved invaluable in achieving high-level control over colloidal synthesis. The success of these so-called seed-mediated pathways has been contingent upon the advancement of synthetic protocols specifically designed to take advantage of the internal defect structures within an otherwise crystalline seed. Noble metal nanoplates represent the most prominent example as their synthesis requires seeds lined with symmetry breaking stacking fault defects that, when placed in a suitably chosen chemical environment, promote two-dimensional heterogeneous deposition. Even though such syntheses are now commonplace, the growth of flat-lying silver nanoplates in arrayed configurations directly on substrate surfaces has heretofore proved unrealizable due to an inability to form appropriately designed seeds in organized patterns. Herein, a silver nanotriangle synthesis is demonstrated on substrate surfaces populated with gold seeds arranged in periodic arrays. Crucial to this success is the relaying of crystallographic information from the substrate to the gold seed to the silver nanotriangle via heteroepitaxy. The so-formed nanotriangles exhibit a tunable plasmon resonance where simulations indicate that the response is dominated by the silver component. The work, hence, adds silver nanotriangles to an ever-expanding list of rationally designed nanostructures accessible through substrate-based syntheses.