https://iopscience.iop.org/article/10.1149/2.0161808jes/pdf

Review—Surface-Enhanced Raman Scattering Sensors for Food Safety and Environmental Monitoring

Performance of portable technologies from mobile phones to electric vehicles is currently limited by the energy density and lifetime of lithium batteries. Expanding the limits of battery technology requires in situ detection of trace components at electrode–electrolyte interphases. Surface-enhance Raman spectroscopy could satisfy this need if a robust and reproducible substrate were available. Gold nanoparticles (Au NPs) larger than 20 nm diameter are expected to greatly enhance Raman intensity if they can be assembled into ordered monolayers. A three-phase self-assembly method is presented that successfully results in ordered Au NP monolayers for particle diameters ranging from 13 to 90 nm. The monolayer structure and Raman enhancement factors (EFs) are reported for a model analyte, rhodamine, as well as the best performing polymer electrolyte salt, lithium bis(trifluoromethane)sulfonimide. Experimental EFs for the most part correlate with predictions based on monolayer geometry and with numerical simula...

Self-Assembly of Large Gold Nanoparticles for Surface-Enhanced Raman Spectroscopy

Surface-enhanced Raman scattering (SERS) is capable of detecting a single molecule with high specificity and has become a promising technique for rapid chemical analysis of agricultural products and foods. With a deeper understanding of the SERS effect and advances in nanofabrication technology, SERS is now on the edge of going out of the laboratory and becoming a sophisticated analytical tool to fulfill various real-world tasks. This review focuses on the challenges that SERS has met in this progress, such as how to obtain a reliable SERS signal, improve the sensitivity and specificity in a complex sample matrix, develop simple and user-friendly practical sensing approach, reduce the running cost, etc. This review highlights the new thoughts on design and nanofabrication of SERS-active substrates for solving these challenges and introduces the recent advances of SERS applications in this area. We hope that our discussion will encourage more researches to address these challenges and eventually help to br...

Facing Challenges in Real-Life Application of Surface-Enhanced Raman Scattering: Design and Nanofabrication of Surface-Enhanced Raman Scattering Substrates for Rapid Field Test of Food Contaminants

Electrochemical energy conversion and storage play crucial roles in meeting the increasing demand for renewable, portable, and affordable power supplies for society The rapid development of nanostructured materials provides an alternative route by virtue of their unique and promising effects emerging at nanoscale In addition to finding advanced materials, structure design and engineering of electrodes improves the electrochemical performance and the resultant commercial competitivity Regarding the structural engineering, controlling the geometrical parameters (ie, size, shape, hetero‐architecture, and spatial arrangement) of nanostructures and thus forming well‐defined nanostructure (WDN) electrodes have been the central aspects of investigations and practical applications This review discusses the fundamental aspects and concept of WDNs for energy conversion and storage, with a strong emphasis on illuminating the relationship between the structural characteristics and the resultant electrochemical superiorities Key strategies for actualizing well‐defined features in nanostructures are summarized Electrocatalysis and photoelectrocatalysis (for energy conversion) as well as metal‐ion batteries and supercapacitors (for energy storage) are selected to illustrate the superiorities of WDNs in electrochemical reactions and charge carrier transportation Finally, conclusions and perspectives regarding future research, development, and applications of WDNs are discussed

Well‐Defined Nanostructures for Electrochemical Energy Conversion and Storage

Surface enhanced Raman scattering (SERS) is a sensitive chemical analysis technique, and the huge Raman enhancement is mainly contributed by surface plasmon resonance of the metal nanoparticles immobilized on support substrates. Compared with the SERS-active nanostructures on rigid supports, the ones on flexible and transparent films provide a non-invasive SERS detection by being attached onto the surface of interest. Moreover, these SERS-active films could be easily reused. Owing to these advantages, these films have attracted much attention in many fields in the past few years. In this review, we have summarized and discussed the recent developments in the fabrication and application of transparent and flexible SERS-active films. First, the fabrication techniques are summarized and divided into four categories, in situ wet chemical synthesis of plasmonic structures, physical deposition of plasmonic metals, nanoparticle adsorption and nanoparticle embedding, based on how plasmonic structures are constructed on flexible substrates. After that, the applications of these SERS-active films are reviewed. They could be used for qualitative and quantitative detection of small molecules, in situ and non-invasive detection of chemical compounds on solid surfaces, spatial mapping of chemical information, as well as for fundamental study. Finally, the challenges and perspectives of this field are presented. It is believed that this review will be helpful for the design, fabrication and application of novel highly efficient SERS systems, especially for real-life applications.

Recent developments of flexible and transparent SERS substrates

Applicable surface enhanced Raman scattering (SERS) active substrates require high enhancement factor (EF), excellent spatial reproducibility, and low-cost fabrication method on a large area. Although several SERS substrates with high EF and relative standard deviation (RSD) of signal less than 5% were reported, reliable fabrication for large area SERS substrates with both high sensitivity and high reproducibility via low-cost routes remains a challenge. Here, we report a facile and cost-effective fabrication process for large-scale SERS substrate with Ag inter-nanoparticle (NP) gaps of 5 nm based on ultrathin alumina mask (UTAM) surface pattern technique. Such closely packed Ag NP arrays with high density of electromagnetic field enhancement (“hot spots”) on large area exhibit high SERS activity and excellent reproducibility, simultaneously. Rhodamine 6G molecules with concentration of 1 × 10–7 M are used to determine the SERS performance, and an EF of ∼109 is obtained. It should be noted that we obtain ...

Highly Reproducible and Sensitive SERS Substrates with Ag Inter-Nanoparticle Gaps of 5 nm Fabricated by Ultrathin Aluminum Mask Technique

The spatial distribution of localized surface plasmon resonance (LSPR) plays a key role in many plasmonic applications. Based on the thermal stability of alumina templates, this work reports a novel approach to manipulate the distribution of LSPR and exhibits its significance for an important plasmonic application, the surface-enhanced Raman spectroscopy (SERS). A suitable thermal annealing sharpens the edges in top surfaces (far from the substrates) of Ag nanoparticles, which significantly strengthens the distal mode (DM) with the LSPR excited on the top surfaces. Because the top surface is the major place to adsorb probe molecules, this manipulation greatly improves the detection sensitivity of SERS. Our research provides a new way to improve the sensitivity of SERS, which also indicates that great care has to be taken on special LSPR mode which is largely responsible for a certain plasmonic application (e.g., the DM for SERS although it is not the major mode).

Effective approach to strengthen plasmon resonance localized on top surfaces of Ag nanoparticles and application in surface-enhanced Raman spectroscopy.

The invention discloses a preparation method of a novel embedded type nano dot array structure surface enhanced Raman active substrate The substrate takes an aluminum sheet with an ordered concave pit array structure on the surface as a template and materials with SERS (Surface Enhanced Raman Scattering) performances are deposited to obtain a large-area and highly-ordered nano dot array structure embedded into a groove on the concave pit substrate The nano dot array provided by the invention can be used for adjusting structure parameters and shapes of the embedded type nano dot array according to the size of the concave pit array, so that different influences on the Raman surface enhancing effect by different embedded type metal nano array substrates are realized The preparation method has the advantages of simplicity in operation, no need of transferring, low cost and easiness for industrial production; the shape of the substrate is highly ordered and the Raman activity is high; and the substrate has the remarkable Raman surface enhancing effect on analytes with different concentrations and has very high detection limit

Embedded type nano dot array surface enhanced Raman active substrate and preparation method thereof

Sensitive and reproducible nanogap SERS substrates for glucose biosensing

A preparing method of an SERS active substrate having a 'hot spot' dimension of less than 5 nm based on a novel high- and low-temperature counterboring process with a step core drill is disclosed. A first time of counterboring is performed at a high temperature that is 30 DEG C to prepare an UTAM the bore diameter of which is 83-87 nm; then a second time of counterboring is performed at a low temperature that is 13-20 DEG C to prepare an UTAM the bore diameter of which is 95-97 nm; metal vacuum thermal resistance type deposition is then performed; and the UTAM is removed to finally prepare the highly-enhanced SERS active substrate the 'hot spot' dimension of which is less than 5 nm. The metal nanometer lattice SERS active substrate the 'hot spot' dimension of which is less than 5 nm is uniform in morphology, controllable in structure and obviously enhanced in Raman signal, the enhancement factor can be 10 , and enhanced signal is uniform and stable. According to the method, based on advantages of UTAM surface nanometer structure preparing techniques, flexible regulation and control of the dimension of minimum hot spots (less than 5 nm) can be achieved conveniently through high- and low-temperature counterboring with the step core drill and by combining vacuum thermal resistance type deposition, and the preparing cost is low, thus facilitating popularization and application of an SERS technique in the field of detection.

A preparing method of an SERS active substrate having a 'hot spot' dimension of less than 5 nm based on a novel high- and low-temperature counterboring process with a step core drill

Xianzheng Zheng

Papers

Highly Reproducible and Sensitive SERS Substrates with Ag Inter-Nanoparticle Gaps of 5 nm Fabricated by Ultrathin Aluminum Mask Technique

Effective approach to strengthen plasmon resonance localized on top surfaces of Ag nanoparticles and application in surface-enhanced Raman spectroscopy.

Embedded type nano dot array surface enhanced Raman active substrate and preparation method thereof

Sensitive and reproducible nanogap SERS substrates for glucose biosensing

A preparing method of an SERS active substrate having a 'hot spot' dimension of less than 5 nm based on a novel high- and low-temperature counterboring process with a step core drill