High-performance SERS Substrates Research Articles

Facile preparation of highly sensitive SERS substrates based on gold nanoparticles modified graphdiyne/carbon cloth

As a new kind of 2D carbon allotrope, graphdiyne (GDY) has the characteristics of uniform pores and large specific surface area due to its unique electronic space arrangement structure. Therefore, we fabricated a novel gold nanoparticles (Au NPs)/GDY/carbon cloth (CC) SERS substrate by a simple electrodeposition process using GDY nanowall wrapping the CC as support. The effects of electrodeposition conditions on the microstructure and SERS activity of Au NPs/GDY/CC substrate were studied. Under the condition of optimizing deposition time and deposition voltage, the prepared Au NPs/GDY/CC substrate can detect 10-13 M with rhodamine 6G (R6G) as a probe molecule. The maximum enhancement factor (EF) is 2.2 × 1012, and the concentration of R6G is logarithmically correlated with the intensity of the SERS band with a linear correlation coefficient (R2) of 0.97036. These indicate that the Au NPs/GDY/CC substrate has good sensitivity. The prepared Au NPs/GDY/CC SERS substrate was applied to the detection of organic dyes of malachite green (MG) and methyl violet (MV) in water, and the detection limits of both can reach 10-9 M. This highly sensitive and high-performance SERS substrate has broad application prospects in the detection of organic dyes.

Rapid and Flexible Construction of Inverted Silicon Architectures with Nanogaps as High-Performance SERS Substrates

Rapid and Flexible Construction of Inverted Silicon Architectures with Nanogaps as High-Performance SERS Substrates

Self-assembled vertically aligned silver nanorod arrays prepared by evaporation-induced method as high-performance SERS substrates

The substrates formed by the self-assembly method of metal nanoparticles are widely used in the molecular detection due to their high uniformity and good SERS properties. In this paper, we used the sliver nanorods as the building block for the first time to produce close-packed vertical arrays via evaporation-induced method. The results showed that the optimized substrates have good performance with excellent enhancement factor (4.47 × 105) and high reproducibility. By the time, we explore the relationship between the length of silver nanorods and the intensity of 4-mercaptobenzoic acid (4-MBA). The optimal SERS performance depended on longest silver nanorod length. In addition, the optimized vertical silver nanorod substrates exhibit 3 times than the optimized six-layer three-dimensional horizontal ones. Furthermore, the optimized substrate was able to directly detect malachite green (MG) down to 10−9 M. At the same time, the on-site detection of the thiram in the peel of apple is as low as 0.1 ng cm−2. The experimental results clearly show that our substrates have great potential for environmental monitoring, food safety and security application.

High performance SERS substrates using high surface roughness gold nanosheets assembled by nanowires

Gold nanosheets were prepared by a solid-state ionics method under a direct current electric field (DCEF) using fast ionic conductor Rb4Cu16Cl13I7 films. The morphology and chemical composition of the gold nanosheets were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS), respectively. Raman enhancement performance of the gold nanosheet substrates was detected by Rhodamine 6G (R6G) aqueous solutions as probe molecules. Gold nanosheets assembled by long-range order and short-range order pure gold nanowires and the nanowires were bamboo-shaped, the diameters of nanowires ranged from 30 to 70 nm. The limiting concentrations of R6G for the prepared gold nanosheet SERS substrates is 10−16 mol/L.

4-Mercaptophenylboronic acid modified Au nanosheets-built hollow sub-microcubes for active capture and ultrasensitive SERS-based detection of hexachlorocyclohexane pesticides

Active capture and ultrasensitive SERS-based detection of hexachlorocyclohexane (HCH) has been a challenging task. A novel strategy based on 4-mercaptophenylboronic acid (4-MPBA) surface modification on Au nanosheets-built hollow sub-microcubes (ANHCs) was proposed to capture HCH pesticides effectively via Suzuki cross coupling reaction. The ANHCs structure composed of numerous intertwined nanosheets was firstly prepared by Au nanocrystals heteroepitaxial growth on AgCl cubes. Then, the 4-MPBA molecules were selected to modify on the surface of ANHCs for SERS-based detection of HCH. The SERS results proved that active capture and ultrasensitive detection of HCH could be implemented, and the limit of detection is 0.3 ppb. Besides, 4-MPBA modified substrate show high reproducibility and sensitivity than unmodified one. Moreover, the characteristic peak intensity ratio IHCH/I4-MPBA presents a good linear relationship with the logarithm of a certain concentrations, and achieve SERS-based quantitative detection of HCH. In addition, this strategy has been successfully used for the detection and differentiation of mixed HCH isomers in water samples. The surface modification strategy on high performance SERS substrate provides a good route for the highly ultrasensitive detection and active capture of HCH, and paves a way for the detection of organochlorine pesticide residues in water samples.

Fabrication and simulation of V-shaped Ag nanorods as high-performance SERS substrates.

Bending straight Ag nanorods (AgNRs) into V-shaped structures can generate a higher surface-enhanced Raman scattering (SERS) performance. Numerical simulations showed that V-shaped AgNRs with a total length between 300 nm and 800 nm were more sensitive than equal-length straight AgNRs under a 785 nm laser in most cases. It was found that at a laser wavelength between 500 nm and 1000 nm, the Raman enhancement factor (EF) of a V-shaped AgNR's 3rd plasmon mode was not only optimal among the other major plasmon modes, but also outperformed the plasmon modes of straight AgNRs. Besides, a linear relationship between the resonance wavelength of the V-shaped AgNR's 3rd mode and its length was observed both numerically and experimentally, which was beneficial for the optimization of SERS substrates. Under 785 nm laser excitation, V-shaped AgNR substrates with a single arm length between 330 nm and 340 nm possessed the highest SERS efficiency. This work took AgNR array substrates one step closer to practical applications.

Uniform arrays of gold nanoparticles with different surface roughness for surface enhanced Raman scattering

Uniform arrays of coarse and smooth gold nanoparticles with diameter about 130 nm were successfully synthesized through seed-mediated growth method, separately. Scanning and transmission electron microscopy (SEM and TEM) and X-ray diffraction (XRD) have been used to study the formation and structure of the nanocomposites. The high enhancement factor for surface-enhanced Raman scattering of coarse and smooth gold nanoparticles were estimated to be about 3.1 × 106 and 2.0 × 106, respectively. It is evident that the coarse gold nanostructures has higher influence factor than the smooth gold nanostructures. Therefore, these unique properties of the coarse Au nanoparticles appear to be very promising for applications as high-performance SERS substrates.

Large-area High-performance SERS Substrates Prepared with a Combination of Mesoporous Silica Film and AuAg Alloy film

Large-area High-performance SERS Substrates Prepared with a Combination of Mesoporous Silica Film and AuAg Alloy film