Abstract
The fabrication of plasmonic nanostructures with a reliable, low cost and easy approach has become a crucial and urgent challenge in many fields, including surface-enhanced Raman spectroscopy (SERS) based applications. In this frame, nanoporous metal films are quite attractive, due to their intrinsic large surface area and high density of metal nanogaps, acting as hot-spots for Raman signal enhancement. In this paper, we report a detailed study on the fabrication of nanoporous silver-based SERS substrates, obtained by the application of two successive treatments with an Inductively Coupled Plasma (ICP) system, using synthetic air and Ar as feeding gases. The obtained substrates exhibit a quite broad plasmonic response, covering the Vis–NIR range, and an enhancement factor reaching 6.5 times, 10^7, estimated by using 4-mercaptobenzoic acid (4-MBA) as probe molecule at 532 nm. Moreover, the substrates exhibit a quite good spatial reproducibility on a centimeter scale, which assures a good signal stability for analytical measurements. Globally, the developed protocol is easy and cost effective, potentially usable also for mass production thanks to the remarkable inter-batches reproducibility. As such, it holds promise for its use in SERS-based sensing platforms for sensitive detection of targets molecules.
Highlights
The fabrication of plasmonic nanostructures with a reliable, low cost and easy approach has become a crucial and urgent challenge in many fields, including surface-enhanced Raman spectroscopy (SERS) based applications
The main advantages of nanoporous SERS substrates concern on (i) the large internal surface available for molecules anchoring, which obviously extends the use of SERS to higher concentrations, and (ii) the high density of hot-spots formed in the nanopores, which assures an adequate enhancement for analyte detection
We propose a rapid, easy, effective and highly reproducible protocol for the fabrication of Ag-based SERS substrates
Summary
The fabrication of plasmonic nanostructures with a reliable, low cost and easy approach has become a crucial and urgent challenge in many fields, including surface-enhanced Raman spectroscopy (SERS) based applications In this frame, nanoporous metal films are quite attractive, due to their intrinsic large surface area and high density of metal nanogaps, acting as hot-spots for Raman signal enhancement. Numerous studies have been reported regarding the use of nanoporous materials for electrocatalytic applications, photovoltaic devices and biosensing platforms, including SERS-based s ensors[22,23,24,25] In this regard, the main advantages of nanoporous SERS substrates concern on (i) the large internal surface available for molecules anchoring, which obviously extends the use of SERS to higher concentrations, and (ii) the high density of hot-spots formed in the nanopores, which assures an adequate enhancement for analyte detection. More reliable substrates are provided by electrochemical dealloying, selective etching in gold-silver alloy, vapor-phase dealloying and sacrificial template a pproaches[26]
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