Lattice-mismatch-induced twinning for seeded growth of anisotropic nanostructures

Synthesis of anisotropic nanostructures from materials with isotropic crystal structures often requires the use of seeds containing twin planes to break the crystalline symmetry and promote the preferential anisotropic growth. Controlling twinning in seeds is therefore critically important for high-yield synthesis of many anisotropic nanostructures. Here, we demonstrate a unique strategy to induce twinning in metal nanostructures for anisotropic growth by taking advantage of the large lattice mismatch between two metals. By using Au-Cu as an example, we show, both theoretically and experimentally, that deposition of Cu to the surface of single-crystalline Au seeds can build up strain energy, which effectively induces the formation of twin planes. Subsequent seeded growth allows the production of Cu nanorods with high shape anisotropy that is unachievable without the use of Au seeds. This work provides an effective strategy for the preparation of anisotropic metal nanostructures.