Abstract
The development of graphene (G) substrates without damage on the sp2 network allows to tune the interactions with plasmonic noble metal surfaces to finally enhance surface enhanced Raman spectroscopy (SERS) effect. Here, we describe a new graphene/gold nanocomposite obtained by loading gold nanoparticles (Au NPs), produced by pulsed laser ablation in liquids (PLAL), on a new nitrogen-doped graphene platform (G-NH2). The graphene platform was synthesized by direct delamination and chemical functionalization of graphite flakes with 4-methyl-2-p-nitrophenyl oxazolone, followed by reduction of p-nitrophenyl groups. Finally, the G-NH2/Au SERS platform was prepared by using the conventional aerography spraying technique. SERS properties of G-NH2/Au were tested using Rhodamine 6G (Rh6G) and Dopamine (DA) as molecular probes. Raman features of Rh6G and DA are still detectable for concentration values down to 1 × 10−5 M and 1 × 10−6 M respectively.
Highlights
Since their discovery, graphene materials (G), due to their outstanding physicochemical properties [1], have generated huge interest in numerous fields including biomedicine, electronics, sensing, energy, etc. [2,3,4,5,6,7,8]
Localized surface plasmon resonance excitation in Ag and Au NPs produces strong extinction and scattering spectra, resulting in amplification of the electric field (E) near the particle surfaces such that |E|2 can be 100–10,000 times greater in intensity than the incident field, which acts on a spatial range of 10–50 nm
The cycloaddition protocol (i.e., 1,3-dipolar cycloaddition between mesoionic compounds and graphite) [31] furnished a G network decorated with ∆-1-pyrrolidine rings, mainly in the edge defected sites. This approach incorporated several interesting advantages: (i) Avoided the damage of sp2 G network; (ii) provided functionalized G with high degree of functionalization (i.e., 4.6%) and the NO2 group on pyrrolidine rings was reduced in good yield (XPS data indicated the reduction of almost half of the nitro groups in NH2 groups); (iii) the amine groups assisted the anchorage of Au NPs produced by pulsed laser ablation in liquids (PLAL) on G surface; (iv) the dispersibility in water of the G-NH2 nanocomposite was enough for its deposition onto glass slide by aerography spraying technique
Summary
Graphene materials (G), due to their outstanding physicochemical properties [1], have generated huge interest in numerous fields including biomedicine, electronics, sensing, energy, etc. [2,3,4,5,6,7,8]. Localized surface plasmon resonance excitation in Ag and Au NPs produces strong extinction and scattering spectra, resulting in amplification of the electric field (E) near the particle surfaces such that |E|2 can be 100–10,000 times greater in intensity than the incident field, which acts on a spatial range of 10–50 nm. These effects are mainly influenced by two factors: (i) NPs morphology (in terms of size and shape) and (ii) local dielectric environment [18,19,20]
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