The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

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Present and Future of Surface-Enhanced Raman Scattering

Stretchability will significantly expand the applications scope of electronics, particularly for large-area electronic displays, sensors and actuators. Unlike for conventional devices, stretchable electronics can cover arbitrary surfaces and movable parts. However, a large hurdle is the manufacture of large-area highly stretchable electrical wirings with high conductivity. Here, we describe the manufacture of printable elastic conductors comprising single-walled carbon nanotubes (SWNTs) uniformly dispersed in a fluorinated rubber. Using an ionic liquid and jet-milling, we produce long and fine SWNT bundles that can form well-developed conducting networks in the rubber. Conductivity of more than 100 S cm(-1) and stretchability of more than 100% are obtained. Making full use of this extraordinary conductivity, we constructed a rubber-like stretchable active-matrix display comprising integrated printed elastic conductors, organic transistors and organic light-emitting diodes. The display could be stretched by 30-50% and spread over a hemisphere without any mechanical or electrical damage.

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Stretchable active-matrix organic light-emitting diode display using printable elastic conductors

Self-assembling aluminium nanoparticles are used to make a plasmon-enhanced device for desalination. Plasmonics has generated tremendous excitement because of its unique capability to focus light into subwavelength volumes1, beneficial for various applications such as light harvesting2,3, photodetection4, sensing5, catalysis6 and so on. Here we demonstrate a plasmon-enhanced solar desalination device, fabricated by the self–assembly of aluminium nanoparticles into a three-dimensional porous membrane. The formed porous plasmonic absorber can float naturally on water surface, efficiently absorb a broad solar spectrum (>96%) and focus the absorbed energy at the surface of the water to enable efficient (∼90%) and effective desalination (a decrease of four orders of magnitude). The durability of the devices has also been examined, indicating a stable performance over 25 cycles under various illumination conditions. The combination of the significant desalination effect, the abundance and low cost of the materials, and the scalable production processes suggest that this type of plasmon-enhanced solar desalination device could provide a portable desalination solution.

3D self-assembly of aluminium nanoparticles for plasmon-enhanced solar desalination

By using an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, we uniformly dispersed single-walled carbon nanotubes (SWNTs) as chemically stable dopants in a vinylidene fluoride-hexafluoropropylene copolymer matrix to form a composite film. We found that the SWNT content can be increased up to 20 weight percent without reducing the mechanical flexibility or softness of the copolymer. The SWNT composite film was coated with dimethyl-siloxane-based rubber, which exhibited a conductivity of 57 siemens per centimeter and a stretchability of 134%. Further, the elastic conductor was integrated with printed organic transistors to fabricate a rubberlike active matrix with an effective area of 20 by 20 square centimeters. The active matrix sheet can be uniaxially and biaxially stretched by 70% without mechanical or electrical damage. The elastic conductor allows for the construction of electronic integrated circuits, which can be mounted anywhere, including arbitrary curved surfaces and movable parts, such as the joints of a robot's arm.

https://science.sciencemag.org/content/sci/321/5895/1468.full.pdf

A Rubberlike Stretchable Active Matrix Using Elastic Conductors

Achieving mastery over the synthesis of metal nanocrystals has emerged as one of the foremost scientific endeavors in recent years. This intense interest stems from the fact that the composition, size, and shape of nanocrystals not only define their overall physicochemical properties but also determine their effectiveness in technologically important applications. Our aim is to present a comprehensive review of recent research activities on bimetallic nanocrystals. We begin with a brief introduction to the architectural diversity of bimetallic nanocrystals, followed by discussion of the various synthetic techniques necessary for controlling the elemental ratio and spatial arrangement. We have selected key examples from the literature that exemplify critical concepts and place a special emphasis on mechanistic understanding. We then discuss the composition-dependent properties of bimetallic nanocrystals in terms of catalysis, optics, and magnetism and conclude the Review by highlighting applications that h...

Bimetallic Nanocrystals: Syntheses, Properties, and Applications

Optically excited plasmonic nanoparticles can activate chemical reactions on their surfaces. The underlying physical mechanisms responsible for the chemical activity and advances in photocatalysis on plasmonic metallic nanostructures are discussed. The strong interaction of electromagnetic fields with plasmonic nanomaterials offers opportunities in various technologies that take advantage of photophysical processes amplified by this light–matter interaction. Recently, it has been shown that in addition to photophysical processes, optically excited plasmonic nanoparticles can also activate chemical transformations directly on their surfaces. This potentially offers a number of opportunities in the field of selective chemical synthesis. In this Review we summarize recent progress in the field of photochemical catalysis on plasmonic metallic nanostructures. We discuss the underlying physical mechanisms responsible for the observed chemical activity, and the issues that must be better understood to see progress in the field of plasmon-mediated photocatalysis.

http://www-nature-com-443.webvpn.bjmu.tsg211.com/articles/nmat4281.pdf

Photochemical transformations on plasmonic metal nanoparticles

Plasmonic metal nanoparticles enhance chemical reactions on their surface when illuminated with light of particular frequencies. It has been shown that these processes are driven by excitation of localized surface plasmon resonance (LSPR). The interaction of LSPR with adsorbate orbitals can lead to the injection of energized charge carriers into the adsorbate, which can result in chemical transformations. The mechanism of the charge injection process (and role of LSPR) is not well understood. Here we shed light on the specifics of this mechanism by coupling optical characterization methods, mainly wavelength-dependent Stokes and anti-Stokes SERS, with kinetic analysis of photocatalytic reactions in an Ag nanocube-methylene blue plasmonic system. We propose that localized LSPR-induced electric fields result in a direct charge transfer within the molecule-adsorbate system. These observations provide a foundation for the development of plasmonic catalysts that can selectively activate targeted chemical bonds, since the mechanism allows for tuning plasmonic nanomaterials in such a way that illumination can selectively enhance desired chemical pathways.

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Evidence and implications of direct charge excitation as the dominant mechanism in plasmon-mediated photocatalysis.

Conductive organic and composite films represent the critical component of many areas of technology. This study demonstrates that highly conductive coatings can be made by layer-by-layer (LBL) assembly of single-walled carbon nanotubes (SWNTs). These films reveal electrical conductivities of 102 to ∼103 S/m at room temperature without doping with nanotube loading as low as ∼10%. This is indicative of efficient utilization of SWNT in percolation pathways. Low SWNT loading also makes the coatings quite transparent with transmission as high as 97% for visible light. Thicker delaminated LBL films displayed conductivities of 4.15 × 104 S/m. The free-standing films were highly flexible and possessed 160 MPa of tensile strength, which makes them the strongest organic conductor. The high strength and conductivities are attributed to the unique homogeneity of the LBL assembled composites, which opens the way to future optimization of electrical, mechanical, and optical properties and to fit the needs of specific a...

Integration of Conductivity, Transparency, and Mechanical Strength into Highly Homogeneous Layer-by-Layer Composites of Single-Walled Carbon Nanotubes for Optoelectronics

Nature Materials 14, 567–576 (2015); published online 20 May 2015; corrected after print 20 May 2015. In the print version of this Review Article the symbols at the two ends of the x axis in Fig. 6a did not render correctly; they should have been Γ. These are correct in the online versions of the Review Article.

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Erratum: Photochemical transformations on plasmonic metal nanoparticles

Electro-chemical and thermo-chemical processes occurring at multi-phase interfaces are the basis of many devices facilitating conversion between forms of energy including solar, electrical, and chemical in a number of devices from fuel cells to batteries. Large electric fields, high potential bias and inherent inaccessibility of these interfaces to many conventional experimental probes contribute to an absence of fundamental insight into mechanistic behavior of chemical species and interfacial environment. Modern first-principles tools including Density Functional Theory (DFT) can be used to study these interfaces from a first-principles approach and provide insight for molecular transformations. In our studies we also coarse-grain DFT calculations with the Cluster Expansion (CE) and extend quantum-mechanical ab-initio information to larger systems and include environmental factors such as temperature, partial pressure of oxygen, and surface morphology (undercoordinated step and edge sites). We investigate two case studies: recharge cycle of lithium/oxygen batteries and oxygen on a metal surface in ethylene epoxidation.

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Matthew Morabito

Papers

Photochemical transformations on plasmonic metal nanoparticles

Evidence and implications of direct charge excitation as the dominant mechanism in plasmon-mediated photocatalysis.

Integration of Conductivity, Transparency, and Mechanical Strength into Highly Homogeneous Layer-by-Layer Composites of Single-Walled Carbon Nanotubes for Optoelectronics

Erratum: Photochemical transformations on plasmonic metal nanoparticles

Oxygen chemistry on transition metals : first principles DFT and Monte Carlo studies.