title: Activation of oxygen-mediating pathway using copper ions: fine-tuning of growth kinetics in gold nanorod overgrowth.
abstract: Growth kinetics plays an important role in the shape control of nanocrystals (NCs). Herein, we presented a unique way to fine-tune the growth kinetics via oxidative etching activated by copper ions. For the overgrowth of gold nanorods (Au NRs), competitive adsorption of dissolved oxygen on rod surface was found to slow down the overgrowth rate. Copper ions were able to remove the adsorbed oxygen species from the Au surface via oxidative etching, thus exposing more reaction sites for Au deposition. In this way, copper ions facilitated the overgrowth process. Furthermore, Cu(2+) rather than Cu(+) acted as the catalyst for the oxidative etching. Comparative study with Ag(+) indicated that Cu(2+) cannot regulate NC shapes via an underpotential deposition mechanism. In contrast, Ag(+) led to the formation of Au tetrahexahedra (THH) and a slight decrease of the growth rate at similar growth conditions. Combining the distinct roles of the two ions enabled elongated THH to be produced. Copper ions activating the O2 pathway suggested that dissolved oxygen has a strong affinity for the Au surface. Moreover, the results of NC-sensitized singlet oxygen ((1)O2) indicated that the absorbed oxygen species on the surface of Au NCs bounded with low-index facets mainly existed in the form of molecular O2.
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology , Beijing 100190, P. R. China.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Liu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Wen
authors.forename: Jiao
authors.initials: J
authors.lastname: Yan
authors.forename: Shuai
authors.initials: S
authors.lastname: Hou
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Shi
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Hu
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Ji
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wu
mesh_terms: D003300:Copper / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D007700:Kinetics; D043942:Nanotubes / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D007477:Ions; D006046:Gold; D003300:Copper; D010100:Oxygen