Speaker
Description
The unusual geometry of spiral nanocrystals gives rise to unique optical, electronic, and mechanical properties. Spiral growth of noble metals was demonstrated for gold decades ago but no information about silver nanospirals was reported. Here present novel approach for preparation of silver nanospirals with yields of over 90%, based on application of 3-mercaptopropionic acid (MPA) ligand. Addition of H2O2 results in formation of different morphologies of silver such as dendrites, nanoribbons, nanospirals or nanoflowers, depending on MPA concentration. Formation of such variety of structures is result of MPA coverage-dependent conformational change and decrease of total nanoparticle surface area during H2O2 addition, causing sudden change from repulsion to attraction of silver nanoparticles. Consequently, rapid 2D oriented assembly launches diffusion-limited auto-accelerated process. When random dendrite arms overlap due to mismatch caused by a rapid growth, this represents the point of spiral formation. Silver morphology can be fine-tuned via MPA/silver nanoparticles ratio, providing therefore a bottom-up route for twisted nanocrystal synthesis within minutes.