Connecting the nanoseed defect structure and crystallinity with resulting nanoparticle products†

Abstract

Anisotropic gold (Au) nanocrystals (NCs) represent an interesting class of materials due to their shape and size dependent tunable optical properties as well as facet dependent catalytic and photocatalytic properties. The morphology of anisotropic Au NCs synthesized via the versatile seed-mediated synthesis is considered to be heavily dependent on the crystallinity and defect structure associated with the initial seed, modified in conjunction with surfactants and/or other shape-directing agents. The seeds can be considered as templates having well defined internal structure and crystal facets on which further atom deposition takes place via heterogeneous nucleation. While defect-structure directed morphological control has been established, the correlation of the seed crystal facets with the final morphology of Au NCs is rarely emphasized. In this study, we draw direct parallels between the crystal structure of the seed and the final morphology of Au NCs. We investigate this area by starting with seeds that have the same dominant crystal structure {111} but with four different morphologies and defect structures. Surprisingly, all the structures led to similar stellated NC products. Our findings open new avenues to evaluate NCs synthesized with seeds containing other crystal facets and exercise morphological control over Au NCs.