title: Galvanic replacement-free deposition of Au on Ag for core-shell nanocubes with enhanced chemical stability and SERS activity.
abstract: We report a robust synthesis of Ag@Au core-shell nanocubes by directly depositing Au atoms on the surfaces of Ag nanocubes as conformal, ultrathin shells. Our success relies on the introduction of a strong reducing agent to compete with and thereby block the galvanic replacement between Ag and HAuCl4. An ultrathin Au shell of 0.6 nm thick was able to protect the Ag in the core in an oxidative environment. Significantly, the core-shell nanocubes exhibited surface plasmonic properties essentially identical to those of the original Ag nanocubes, while the SERS activity showed a 5.4-fold further enhancement owing to an improvement in chemical enhancement. The combination of excellent SERS activity and chemical stability may enable a variety of new applications.
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Yin
authors.initials: Y
authors.lastname: Yang
authors.forename: Jingyue
authors.initials: J
authors.lastname: Liu
authors.forename: Zheng-Wen
authors.initials: ZW
authors.lastname: Fu
authors.forename: Dong
authors.initials: D
authors.lastname: Qin
mesh_terms: D002712:Chlorides / Q000737:chemistry; D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry*; D017612:Gold Compounds / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D053761:Nanocomposites / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods; D010084:Oxidation-Reduction; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation / Q000379:methods; D013499:Surface Properties
chemical_list: D002712:Chlorides; D017612:Gold Compounds; D012834:Silver; D006046:Gold; C024568:gold tetrachloride, acid