2022, Ni, Bing, Cölfen, Helmut

Seed-mediated growth methods have been widely adopted to fabricate nanoparticles (NPs) with uniform shapes and narrow size distributions. Here we systematically investigate the role of seeds to the final morphologies by studying the shape evolution of mini Au nanorods (NRs, 11.6 nm in length and 3.7 nm in width) in different growth environments from the perspective of the symmetry-based kinematic theory (SBKT). The SBKT emphasizes more the crystal growth processes than the thermodynamic stability of the final structures. According to the SBKT, it is the growth habit of the growing nanoparticles depending on the reaction systems, but not the seeds themselves, that dominates the shape evolution. The growth habits mainly include the preferential growth directions (PGDs) and the properties of the kinematic waves. The results overall supported that (1) if the growth habit was not significantly changed, the NP symmetry could be maintained and the monodispersity of the final products would increase; (2) if the growth habit has changed a lot, the NR symmetry could be maintained under conditions with significant coherent growth; (3) otherwise, the NR symmetry would be repaired to that of the lattice.