title: Tuning the surface enhanced Raman scattering and catalytic activities of gold nanorods by controlled coating of platinum.
abstract: Galvanic replacement of silver (Ag) by platinum (Pt) on bi-metallic nanorods (NRs) having gold (Au) core and silver shell (Au@Ag) resulted in discontinuous coating of Pt over Au (Au@Pt-DC) NRs. However, a novel method has been developed in this work for the preparation of Au NRs having smooth and continuous coating of Pt (Au@Pt-C NRs) using galvanic replacement reaction of Au@Ag NRs in presence of sulphuric acid. Selective blocking by the bisulfate ions that are adsorbed on Pt surface, preventing Pt on Pt deposition seems to be the mechanism of formation of Au@Pt-C NRs. Effect of the nature of Pt shell (i.e. whether continuous or discontinuous) on SERS activity of the NRs was investigated with methylene blue (MB) as a reporter molecule. The specific enhancement of the Raman signals were in the order Au@ Pt-C NRs<Au NR<Au@Pt-DC NRs. Catalytic reduction of MB by NaBH4 using the NRs also followed a similar trend with Au@Pt-DC NRs showing almost three times better activity than Au and Au@Pt-C NRs.
authors.affiliation: School of Basic Sciences, Indian Institute of Technology Mandi, Himachal Pradesh 175005, India.
authors.forename: Vipul
authors.initials: V
authors.lastname: Sharma
authors.affiliation: Department of Mechanical Engineering, Indian Institute of Technology Kanpur, 208016, India.
authors.forename: Niraj
authors.initials: N
authors.lastname: Sinha
authors.affiliation: School of Basic Sciences, Indian Institute of Technology Mandi, Himachal Pradesh 175005, India.
authors.forename: Sunil
authors.initials: S
authors.lastname: Dutt
authors.affiliation: School of Basic Sciences, Indian Institute of Technology Mandi, Himachal Pradesh 175005, India.
authors.forename: Mohit
authors.initials: M
authors.lastname: Chawla
authors.affiliation: School of Basic Sciences, Indian Institute of Technology Mandi, Himachal Pradesh 175005, India. Electronic address: prem@iitmandi.ac.in.
authors.forename: Prem Felix
authors.initials: PF
authors.lastname: Siril
keywords: Core–shell nanorods; Dye reduction; Galvanic replacement; Gold nanorods; SERS