This paper describes a facile method that generates dimers of Ag nanospheres by etching Ag nanocubes with Fe(NO 3 ) 3 in ethanol with the assistance of poly(vinyl pyrrolidone) (PVP). During the etching process, the corners and edges of the Ag nanocubes were truncated off to generate spherical particles, accompanied by dimerization as a result of reduction in colloidal stability due to the addition of ionic species. Both ethanol and PVP play an important role in the etching and dimerization processes. By starting with Ag nanocubes of different sizes, we obtained welldefined dimers of Ag spheres 40, 63, and 80 nm in diameter with percentages of dimerization >60%. Since this approach can be used to fabricate dimers of Ag nanospheres with a range of different sizes, it allows for a systematic study of the hot-spot phenomenon in SERS. By correlating with SEM imaging, we measured the SERS enhancement factors for individual dimers from the three different samples, and an average value of 3.9×10 7 , 9.3×10 7 , and 1.7×10 8 was obtained, respectively.

Progress in practical applications of large, passively collected data sets is often hindered by the lack of appropriate analytical tools or the proprietary nature of applicable software. One of the most widely used data sources in the United States is truck GPS data that are commercially available from a few sources nationwide. Although many large GPS data sets are used in the development of tour-based truck models, the development of a fairly general approach to data analysis and processing that can be readily applied to various GPS data sets without need of proprietary software is still of interest. First, this paper presents a set of tools and techniques used to transform low-frequency truck GPS data available from commercial sources into complete trajectories on the network, that is, sequences of links constituting continuous paths traversed by each truck, with corresponding time stamps on each of the nodes. For this exercise, only open-source software was used, and the algorithm implementation was released as an open-source tool under a business-friendly license. Second, use of the truck GPS data was expanded beyond the standard extraction of trip matrices and estimation of tour models. Additional applications include select link analysis, time-of-day analysis, and trajectory data visualization.

Hotspots können die Empfindlichkeit der oberflächenverstärkten Raman‐Streuung (SERS) stark erhöhen, doch erklärt werden konnte dieses Phänomen bisher nicht. Eine neue Strategie (siehe Bild) setzt auf das Plasmaätzen, um an Hotspots zwischen zwei Silbernanowürfeln adsorbierte SERS‐aktive Moleküle zu isolieren und gezielt zu untersuchen.magnified image

Although catalytic processes mediated by surface plasmon resonance (SPR) excitation have emerged as an ew frontier in catalysis,t he selectivity of these processes remains poorly understood. Here,t he selectivity of the SPR-mediated oxidation of p-aminothiophenol (PATP) employing Au NPs as catalysts was controlled by the choice of catalysts (Au or TiO 2 -Au NPs) and by the modulation of the charge transfer from UV-excited TiO 2 to Au.W hen Au NPs were employed as catalyst, the SPR-mediated oxidation of PATP yielded p,pdimercaptobenzene (DMAB). When TiO 2 -Au NPs were employed as catalysts under both UV illumination and SPR excitation, p-nitrophenol (PNTP) was formed from PATP in as ingle step.I nterestingly,P NTP molecules were further reduced to DMAB after the UV illumination was removed. Our data showthat control over charge-transfer processes may play an important role to tune activity,product formation, and selectivity in SPR-mediated catalytic processes.

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Nanorattles,c omprised of an anosphere inside an anoshell, were employed as the next generation of plasmonic catalysts for oxidations promoted by activated O 2 . After investigating how the presence of an anosphere inside an anoshell affected the electric-field enhancements in the nanorattle relative to an anoshell and an anosphere,t he SPRmediated oxidation of p-aminothiophenol (PATP) functionalized at their surface was investigated to benchmark howt hese different electric-field intensities affected the performances of Au@AgAu nanorattles,A gAun anoshells and Au nanoparticles having similar sizes.T he high performance of the nanorattles enabled the visible-light driven synthesis of azobenzene from aniline under ambient conditions.A st he nanorattles allowt he formation of electromagnetic hot spots without relying on the uncontrolled aggregation of nanostructures,i t enables their application as catalysts in liquid phase under mild conditions using visible light as the main energy input.Oxidation reactions play ap ivotal role in industrial processes and academic research, [1][2][3] in which the activation of molecular oxygen (O 2 )a tt he catalyst surface represents apromising alternative to achieve high activities. [4][5][6] Interestingly,i th as been demonstrated that the surface plasmon resonance (SPR) excitation in silver (Ag) and gold (Au) nanostructures can generate activated O 2 at the metal surface. [7][8][9][10][11][12] This process occurs through the charge transfer of SPR-excited hot electrons to adsorbed O 2 molecules,allowing the use of visible-light to drive oxidation reactions. [7][8][9][10][11][12] Most studies on SPR-mediated transformations have focused on first-generation plasmonic catalysts,t hat is,c onventional Ag and Au nanoparticles such as quasi-spheres, cubes,wires,plates,among others. [7][8][9][10][11][12] Herein, we propose the utilization of metallic nanorattles,comprised of ananosphere inside of an anoshell, as the next generation of plasmonic catalysts towards SPR-mediated oxidations by taking advantage of the plasmon hybridization concept. [13,14] In nanorattles, plasmon hybridization between the nanoshell and nanosphere components can lead to much higher electric field (E-field) enhancements relative to its individual counterparts. [15][16][17] Nanorattles also enable the generation of electromagnetic hot spots in ac ontrollable manner without relying on the uncontrolled aggregation among individual nanostructures. [18,19] This is not possible in first-generation plasmonic catalysts,a nd aggregation leads to ad ecrease in surface area and thus catalytic performance.P reviously,h igh efficiencies towards SPR-mediated transformations were described at junctions between Ag nanocubes supported over Al 2 O 3 . [20] Although these junctions could present higher E-field enhancements relative to the nanorattles,t heir formation still relies on the uncontrolled aggregation and the synthesis of nanocubes is more complex relative to spherical nanoparticles.F inally,p rocedures for...

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Prussian blue analogs (PBAs) are promising catalysts for green hydrogen production. However, the rational design of high‐performing PBAs is challenging, which requires an in‐depth understanding of catalytic mechanism. Here FeMn@CoNi core‐shell PBAs were employed as precursors, together with Se powders, in low‐temperature pyrolysis in an argon atmosphere. This synthesis method enabled the partial dissociation of inner FeMn PBAs that resulted in hollow interiors, Ni nanoparticles (NPs) exsolution to the surface, and Se incorporation onto the PBA shell. The resulting material presented ultra‐low oxygen evolution reaction (OER) overpotential (184 mV at 10 mA cm−2) and low Tafel slope (43.4 mV dec−1), outperforming leading‐edge PBA‐based electrocatalysts. The mechanism responsible for such a high OER activity was revealed, assisted by DFT calculations and the surface examination before and after the OER process. The exsolved Ni NPs were found to help turn the PBAs into Se‐doped core‐shell metal oxyhydroxides during the OER, in which the heterojunction with Ni and the Se incorporation were combined to improve the OER kinetics. This work shows that efficient OER catalysts could be developed by using a novel synthesis method backed up by a sound understanding and control of the catalytic pathway.This article is protected by copyright. All rights reserved