Combined Visible Plasmons of Ag Nanoparticles and Infrared Plasmons of Graphene Nanoribbons for High‐Performance Surface‐Enhanced Raman and Infrared Spectroscopies

Abstract

Ag nanoparticles (NPs) modified graphene nanoribbons (GNRs) are proposed to function as the high‐performance shared substrates for surface‐enhanced Raman and infrared absorption spectroscopy (SERS and SEIRAS). This is realized by modulating the localized plasmonic resonances of Ag NPs in visible region and GNRs in mid‐infrared region simultaneously, so as to selectively employ each resonance to acquire SERS and SEIRAS on a single substrate. As a proof of concept, shared substrates are prepared by fabricating GNRs on a Fabry–Pérot like cavity, followed by depositing a thin Ag film with annealing treatment to achieve Ag NPs. Complementary Raman and infrared active vibrational modes of rhodamine 6G molecules can be extracted from the SERS and SEIRAS spectra. By optimizing the dimension of Ag NPs, SERS enhancement factors at the order of 105 can be achieved, which are comparable with or even larger than that of the reported shared substrates. Meanwhile, various polyethylene oxide vibrational modes can be recognized with maximum SEIRAS amplification up to 170 times, which is one order larger than that of the reported graphene plasmonic infrared sensors. Such plasmonic nanosensor with excellent SERS and SEIRAS performance exhibits promising potential for biosensing applications on an integrated lab‐on‐a‐chip strategy.

Nanostructured Surfaces as Plasmonic Biosensors: A Review

“…In fact, optoelectronic device performance can be boosted by combing graphene with metal nanoparticles. [147,148] For example, Nong et al [136] realized a hybrid nanostructure consisting of AgNPs-modified graphene nanoribbons (GNRs) (Figure 12e-1) to obtain a double-resonant plasmonic platform: one in the visible range and the other in the MIR region produced by AgNPs and GNRs, respectively (Figure 12e-2). Such a hybrid nanostructure allows one to separately tune both the plasmon resonances; in particular, the GNRs can be adjusted by varying the nanoribbon widths and spacing.…”

“…Copyright 2019, IOP Publishing Ltd. e-1) Sketch of the hybrid AgNPs-modified GNR nanostructure (top panel) and SEM images of bare GNRs (left-bottom panel) and AgNPs-modified GNRs (right-bottom panel), e-2) Simulated extinction spectra (top panel) and electric field enhancement (bottom panel) of the hybrid substrate at visible and IR frequencies, e-3) absorption spectra of the substrate with (solid red line) and without (solid gray line) R6G coating. Adapted with permission [136]. Copyright 2020, Wiley-VCH.…”

Enhanced Molecular Infrared Spectroscopy Employing Bilayer Graphene Acoustic Plasmon Resonator

“…Compared to plasmons in traditional noble metals, graphene is two-dimensional (2D) nanomaterials that have been demonstrated to support localized surface plasmons with considerable field confinement in the infrared region, which offer a new class of platform to realize novel electronic and photonic devices in ultracompact sizes [ 11 , 12 , 13 ]. With the advantages of low propagation loss and actively tunable resonance wavelength in the infrared region, graphene plasmons (GPs) exhibit unique features that are not available in traditional metallic surface plasmons and have been widely used in infrared spectroscopy [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Recently, it was demonstrated that graphene plasmons can be tuned and enhanced by double or multi-layer graphene nanostructures [ 21 , 22 ].…”

Plasmonic Core–Shell–Satellites with Abundant Electromagnetic Hotspots for Highly Sensitive and Reproducible SERS Detection

“…SERS is a non-destructive, highly sensitive, and powerful vibrational spectroscopy technique that amplifies the Raman signal of probe molecules and can detect a low concentration of molecules by exploiting the advantages of the LSPR effect on metallic NPs [16][17][18]. Generally, Ag and Au are considered as pivotal materials for highly active SERS substrates due to the intense LSPR and strong electromagnetic (EM) field across the visible region of the electromagnetic spectrum [19,20].…”