title: Observing reduction of 4-nitrobenzenthiol on gold nanoparticles in situ using surface-enhanced Raman spectroscopy.
abstract: In this article, reduction of 4-nitrobenzenthiol (4-NBT) on Au nanoparticles (NPs) was characterized using surface-enhanced Raman scattering (SERS). Plasmon-driven chemical transformation from 4-NBT dimering into p,p'-dimercaptoazobenzene (DMAB) has been investigated on the surface of Au NPs. The laser power-dependent SERS spectra of 4-NBT on the surface of Au substrates were studied, and show that the laser power has an influence on the SERS signals of 4-NBT on Au NPs and production of DMAB by a plasmon-driven surface-catalyzed chemical reaction tends to be much easier under relative high laser power. Furthermore, we have used simple and efficient Au substrates (gold NPs with a size around 45 nm) exhibiting both catalytic properties and SERS activities to monitor the catalytic reaction of surface catalytic reaction process with borohydride solution. The experiments prove that the nitro-to-amino group conversion could be completed by borohydride at ambient conditions on Au substrates. Illuminated with high laser power, 4-NBT molecules and already formed DMAB molecules are further reduced into 4-aminobenzenthiol (4-ABT) by the addition of borohydride, While with low laser power 4-NBT molecules are transformed into 4-ABT with DMAB as the intermediate, which proves Au NPs are a mild and promising catalyst. Our studies might be helpful in extending the understanding of chemical reactions of 4-NBT and related research as well as providing a new strategy synthesis of azo dyes and anilines.
authors.affiliation: Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191, PR China.
authors.forename: Xiaoqian
authors.initials: X
authors.lastname: Ren
authors.forename: Enzhong
authors.initials: E
authors.lastname: Tan
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Lang
authors.forename: Tingting
authors.initials: T
authors.lastname: You
authors.forename: Li
authors.initials: L
authors.lastname: Jiang
authors.forename: Hongyan
authors.initials: H
authors.lastname: Zhang
authors.forename: Penggang
authors.initials: P
authors.lastname: Yin
authors.forename: Lin
authors.initials: L
authors.lastname: Guo
mesh_terms: D001894:Borohydrides / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013059:Spectrum Analysis, Raman; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: C586463:4-nitrobenzenthiol; D001894:Borohydrides; D009574:Nitro Compounds; D013438:Sulfhydryl Compounds; C568766:p,p'-dimercaptoazobenzene; D006046:Gold