title: Copper-ion-assisted growth of gold nanorods in seed-mediated growth: significant narrowing of size distribution via tailoring reactivity of seeds.
abstract: In the well-developed seed-mediated growth of gold nanorods (GNRs), adding the proper amount of Cu(2+) ions in the growth solution leads to significant narrowing in the size distribution of the resultant GNRs, especially for those with shorter aspect ratios (corresponding longitudinal surface plasmon resonance (LSPR) peaks shorter than 750 nm). Cu(2+) ions were found to be able to catalyze the oxidative etching of gold seeds by oxygen, thus mediating  subsequent growth kinetics of the GNRs. At proper Cu(2+) concentrations, the size distribution of the original seeds is greatly narrowed via  oxidative etching. The etched seeds are highly reactive and grow quickly into desired GNRs with significantly improved size distribution. A similar mechanism can be employed to tune the end cap of the GNRs. Except for copper ions, no observable catalytic effect is observed from other cations presumably due to their lower affinity to oxygen. Considering the widespread use of seed-mediated growth in the morphology-controlled synthesis of noble metal nanostructures, the tailoring in seed reactivity we presented herein could be extended to other systems.
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wen
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Hu
authors.forename: Wenqi
authors.initials: W
authors.lastname: Liu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Shuai
authors.initials: S
authors.lastname: Hou
authors.forename: Xiaona
authors.initials: X
authors.lastname: Hu
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wu
mesh_terms: D002413:Cations, Divalent / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D020349:Surface Plasmon Resonance / Q000379:methods
chemical_list: D002413:Cations, Divalent; D006046:Gold; D003300:Copper