Superhydrophobic 3D Forest‐Like Ag Microball/Nanodendrite Hierarchical Structure as SERS Sensor for Rapid Droplets Detection

Abstract

are dedicated to find a facile and easy way preparing the 3D nanostructures with outstanding SERS performance. [17,18] Electrochemical deposition approach was commonly used for fabrication of nanostructures to obtain high catalytic effectiveness on electrodes. [19,20] It has been considered as a rapid and low-cost method for synthesizing SERS substrates in recent years. [21,22] Morphology of the substrates can be easily controlled by adjusting the voltage, constant and concentration of the analyte, greatly improving the preparing efficiency.Surface superhydrophobicity have drawn much attention in various fields for its self-cleaning and recyclable properties. [23] The surface micro/nanostructures and surface low energy modification are both needed for generating superhydrophobicity. [24] Studies on preparing SERS substrates with superhydrophobicity have been explored gradually, normally utilizing aggregation of the probe molecule droplets to enhance the detection limit. [25][26][27] However, directly using the self-cleaning property can offer more advantages for practical application of the substrate. Shin et al. prepared a novel SERS sensor with low adhesive property to detect the droplets rapidly for real-time chemical and biological monitoring. [28] Traditional SERS detection is usually proceeded by drying the probe molecule solution on substrates for contacting with the noble metal nanostructures, which needs several hours' immersing time. [29,30] If sample droplets can be tested directly on the substrate, it will greatly improve the testing efficiency and be available in practical application.We designed a 3D Ag forest-like micro/nanostructure by electrochemical deposition of Ag nanodendrites on the Ag microwool ball structures, acting as an upholder for the nanodendrites vertically growing. The deposition process was facile and needed only several minutes to generate the structures. Superior SERS performance of the substrate was verified by comparing different morphologies with Ag nanodendrites or microball structures growing on film and electromagnetic field distribution simulation. The superiority was caused by the standing nanotips on the dendrites and nanogaps among the standing Ag nanodendrites. Superhydrophobicity was induced to the substrate for the purpose of rapid detecting. Directly SERS detections on sample droplets were tested with detection Real environment detection application by surface-enhanced Raman scattering (SERS) requires substrates with high sensitivity, rapid detection, and low cost. In this study, a rapid SERS detection of liquid droplets sample by a superhydrophobic 3D forest-like Ag microball/nanodendrite hierarchical structure is reported. Easy preparation is provided by electrochemical deposition method, developing a Ag forest-like hierarchical nanostructure. The vertically standing nanodendrites offer more amounts of SERS "hot spots" for enhancing the Raman signals. At the same time, the micro/nanostructures supply suitable condition for superhydrophobicity by low surface energ...

Smart design of high‐performance surface‐enhanced Raman scattering substrates

“…Other nanostructures with sharp tips, edges, or corners are designed to improve the SERS activity, such as bowtie, 27 dendritic, 28–30 nanocaps, nanotriangles, 31,32 nanoprisms, and hedgehog (Figure 2A–D). 33,34 Although these nanoparticles with various morphologies effectively enhance the local electromagnetic field, the nonuniform distribution of nanoparticles will lead to uneven and unstable SERS signals.…”

“…(B) Dendritic. Reproduced with permission: Copyright 2019, Wiley 30 . (C) Nanocaps and nanotriangles.…”

From Dilute to Multiple Layers: Bottom‐Up Self‐Assembly of Rough Gold Nanorods as SERS Platform for Quantitative Detection of Thiram in Soil

“…[ 50 ] Compared with conventional low‐dimensional substrates, 3D SERS substrates provide many merits including more hotspots through the 3D plasmonic coupling and larger overall surface area, thus improving the SERS signal. [ 51–54 ] Typically, the 3D Ag NRs SERS substrates were prepared through layer‐by‐layer self‐assembly technique, and achieved stronger SERS enhancement than the conventional substrates. [ 55 ] In addition, the effect of plasmonic coupling on the SERS property was explored in detail by preparing “0D” to “3D” nanostructures through the assembly of Ag NCs.…”

Fabrication optimization and application of 3D hybrid SERS substrates

“…Conveniently, the shape and size of the assembly unit can be well regulated at a low cost and a short preparation time. [34][35][36] The single-layer nanoparticles could be carefully laid on the air-liquid interface using the self-assembly technique, making it feasible to prepare various types of ordered nanostructures SERS substrates with different shapes of nanoparticles. 20,37,38 Moreover, the layer-by-layer stacking of monolayer nanoparticles made it possible to fabricate structures with exact layers and study the correlation between 3D plasmonic coupling and SERS properties of the 3D hierarchical SERS 19 or detect small biological molecules.…”