Abstract
We report the synthesis, characterization and use of a robust surface enhanced Raman spectroscopy platform with a stable detection for up to one year of Rhodamine R6G at a concentration of 10−6M. The detection of aminothiophenol and methyl parathion, as active molecules of commercial insecticides, is further demonstrated at concentrations down to 10−5–10−6M. This platform is based on large scale textured few-layer (fl) graphene obtained without any need of graphene transfer. The synthesis route is based on diamond-like carbon films grown by pulsed laser deposition, deposited onto silicon substrates covered by a Ni layer prior to diamond-like carbon deposition. The formation of fl-graphene film, confirmed by Raman spectroscopy and mapping, is obtained by thermal annealing inducing the diffusion of Ni atoms and the concomitant formation of nickel silicide compounds, as identified by Raman and Auger electron spectroscopies. The textured fl-graphene films were decorated with gold nanoparticles to optimize the efficiency of the SERS device to detect organic molecules at low concentrations.
Highlights
The design of graphene architectures has become a stake for the fabrication of advanced materials with various functionalities
The formation of large scale textured graphene on Si substrate is a competition of two dynamical reactions during thermal heating involving different interfacial reactions (Kirkendall planes): a diffusion and precipitation of carbon on the surface of unreacted Ni film according to the aforementioned mechanism and a precipitation of carbon from silicides compounds supersaturated with carbon [31,32]
surface-enhanced Raman scattering (SERS) enhancement typically comes from a change in Raman polarizability which refers to the chemical mechanism (CM) and a change in local field which corresponds to the electromagnetic mechanism (EM) [43,44]
Summary
The design of graphene architectures has become a stake for the fabrication of advanced materials with various functionalities. New approaches have been reported to provide a better surface control synthesis and coverage of NPs on r-GO [14,15], alternative graphene platforms are still needed to be developed for the simplest preparation method, large scale and sensitive detection of molecular fingerprints. We have obtained the conversion of 20 nm diamond-like carbon (DLC), deposited by PLD and covered by a thin film of nickel, into few-layers (fl) of graphene [22] In this manuscript, we introduce a new sensitive and stable SERS substrate for environmental applications. The easy formation of 3D porous and textured graphene is explained by the diffusion of nickel into the silicon at the interface and the formation of silicides This new system has been used as a highly stable SERS platform, using gold nanoparticles (Au NPs) deposited on the fl-graphene. Commercial insecticides, aminothiophenol and methyl parathion, have been detected with a sensitivity which has never been observed before, with high stability confirmed after one year under ambient conditions
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